0x2B|~0x2B – Page 6 – My broken wings still strong enough to cross the ocean with.

Mount Samba Share as a Non-root User

April 9, 2015 by gonwan·0 Comments

I used to access windows share folders directly in nautilus, or mount them like:

# mount -t cifs -o username=<your_username>,password=<your_password> //<your_server>/<your_share> /mnt/<your_local>

1	# mount -t cifs -o username=<your_username>,password=<your_password> //<your_server>/<your_share> /mnt/<your_local>

The problem is, they can be accessed only by root. The solution is adding a simple uid option like:

# sudo mount -t cifs -o uid=<your_uid>,username=<your_username>,password=<your_password>,domain=<your_domain> //<your_server>/<your_share> /mnt/<your_local> -vvv

1	# sudo mount -t cifs -o uid=<your_uid>,username=<your_username>,password=<your_password>,domain=<your_domain> //<your_server>/<your_share> /mnt/<your_local> -vvv

See: http://wiki.centos.org/TipsAndTricks/WindowsShares

Updated June 1, 2015:

You may encounter 121 error like:

mount error(121): Remote I/O error
Refer to the mount.cifs(8) manual page (e.g. man mount.cifs)

1 2	mount error(121): Remote I/O error Refer to the mount.cifs(8) manual page (e.g. man mount.cifs)

It’s a Windows side issue, set following registry value to 3. This value tells Windows to prioritize file sharing over reducing memory usage.

HKLM\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters\Size

1	HKLM\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters\Size

Reboot (or just restart the “Server” service in services.msc). Your problem should now be solved.

See: https://boinst.wordpress.com/2012/03/20/mount-cifs-cannot-allocate-memory-mounting-windows-share/

MySQL with C++ and Python

March 26, 2015 by gonwan·0 Comments

Backup here:

1. C++

/*
 * # gcc test_mysql.c -o test_mysql -lmysqlclient -pedantic -Wall -Wextra
 */
#include <stdio.h>
#include <mysql/mysql.h>

int main()
{
    const char *host = "192.168.1.101";
    const char *user = "root";
    const char *pass = "111111";
    const char *dbname = "mysql";
    MYSQL mysql;
    MYSQL_RES *mysql_res;
    MYSQL_FIELD *mysql_field;
    MYSQL_ROW mysql_row;
    unsigned int num_fields;
    unsigned long num_rows;
    int i, rc;

    mysql_init(&mysql);
    /* connect */
    if (!mysql_real_connect(&mysql, host, user, pass, dbname, 0, NULL, 0)) {
        fprintf(stderr, "ERROR: %s\n", mysql_error(&mysql));
        return -1;
    }
    /* query */
    rc = mysql_query(&mysql, "SELECT * FROM user");
    if (rc) {
        fprintf(stderr, "ERROR: %s\n", mysql_error(&mysql));
        mysql_close(&mysql);
        return -1;
    }
    /* display */
    mysql_res = mysql_store_result(&mysql);
    if (!mysql_res) {
        fprintf(stderr, "ERROR: %s\n", mysql_error(&mysql));
        mysql_close(&mysql);
        return -1;
    }
    num_fields = mysql_num_fields(mysql_res);
    printf("fields: %u\n", num_fields);
    num_rows = (unsigned long)mysql_num_rows(mysql_res);
    printf("rows: %lu\n", num_rows);
    if (num_rows != 0) {
        num_fields = (num_fields <= 9) ? num_fields : 9;
        for (i = 0; i < (int)num_fields; i++) {
            mysql_field = mysql_fetch_field_direct(mysql_res, i);
            printf("%s\t", mysql_field->name);
        }
        printf("\n");
        while ((mysql_row = mysql_fetch_row(mysql_res)) != NULL) {
            for (i = 0; i < (int)num_fields; i++) {
                printf("%s\t",  mysql_row[i]);
            }
            printf("\n");
        }
    }
    mysql_free_result(mysql_res);
    mysql_close(&mysql);
    return 0;
}

* # gcc test_mysql.c -o test_mysql -lmysqlclient -pedantic -Wall -Wextra

#include <stdio.h>

#include <mysql/mysql.h>

int main()

{

const char *host = "192.168.1.101";

const char *user = "root";

const char *pass = "111111";

const char *dbname = "mysql";

MYSQL mysql;

MYSQL_RES *mysql_res;

MYSQL_FIELD *mysql_field;

MYSQL_ROW mysql_row;

unsigned int num_fields;

unsigned long num_rows;

int i, rc;

mysql_init(&mysql);

/* connect */

if (!mysql_real_connect(&mysql, host, user, pass, dbname, 0, NULL, 0)) {

fprintf(stderr, "ERROR: %s\n", mysql_error(&mysql));

return -1;

}

/* query */

rc = mysql_query(&mysql, "SELECT * FROM user");

if (rc) {

fprintf(stderr, "ERROR: %s\n", mysql_error(&mysql));

mysql_close(&mysql);

return -1;

}

/* display */

mysql_res = mysql_store_result(&mysql);

if (!mysql_res) {

fprintf(stderr, "ERROR: %s\n", mysql_error(&mysql));

mysql_close(&mysql);

return -1;

}

num_fields = mysql_num_fields(mysql_res);

printf("fields: %u\n", num_fields);

num_rows = (unsigned long)mysql_num_rows(mysql_res);

printf("rows: %lu\n", num_rows);

if (num_rows != 0) {

num_fields = (num_fields <= 9) ? num_fields : 9;

for (i = 0; i < (int)num_fields; i++) {

mysql_field = mysql_fetch_field_direct(mysql_res, i);

printf("%s\t", mysql_field->name);

}

printf("\n");

while ((mysql_row = mysql_fetch_row(mysql_res)) != NULL) {

for (i = 0; i < (int)num_fields; i++) {

printf("%s\t", mysql_row[i]);

}

printf("\n");

}

mysql_free_result(mysql_res);

mysql_close(&mysql);

return 0;

}

2. Python

#!/usr/bin/python
# sudo apt-get install python-mysql.connector
# sudo apt-get install python3-mysql.connector
from __future__ import print_function
import mysql.connector

cur = None
con = None

try:
    con = mysql.connector.connect(host='192.168.1.101', user='root', password='111111', database='mysql')
    cur = con.cursor()
    cur.execute("SELECT * FROM user")
    num_fields = len(cur.column_names)
    print('fields: %d' % num_fields)
    if num_fields > 9:
        num_fields = 9
    rows = cur.fetchall()  # fetchall() before get rowcount
    print('rows: %d' % cur.rowcount)
    for i in range(num_fields):
        print('%s\t' % (cur.column_names[i]), end='')
    print()
    for row in rows:
        for i in range(num_fields):
            print('%s\t' % (row[i]), end='')
        print()
except mysql.connector.Error as e:
    print(e)
finally:
    if cur:
        cur.close()
    if con:
        con.close()

#!/usr/bin/python

# sudo apt-get install python-mysql.connector

# sudo apt-get install python3-mysql.connector

from __future__ import print_function

import mysql.connector

cur = None

con = None

try:

con = mysql.connector.connect(host='192.168.1.101', user='root', password='111111', database='mysql')

cur = con.cursor()

cur.execute("SELECT * FROM user")

num_fields = len(cur.column_names)

print('fields: %d' % num_fields)

if num_fields > 9:

num_fields = 9

rows = cur.fetchall() # fetchall() before get rowcount

print('rows: %d' % cur.rowcount)

for i in range(num_fields):

print('%s\t' % (cur.column_names[i]), end='')

print()

for row in rows:

for i in range(num_fields):

print('%s\t' % (row[i]), end='')

print()

except mysql.connector.Error as e:

print(e)

finally:

if cur:

cur.close()

if con:

con.close()

Qt4学习笔记 (7)

January 22, 2015 by gonwan·0 Comments

This is a repost from my previous Qt learning series, based on Qt 4.3.

本篇说一下Qt对于脚本的支持, 即QtScript模块.

    Qt支持的脚本基于ECMAScript脚本语言, 这个东西又是javascript, jscript的基础. 所以, 一般只要学过javascript就基本会写Qt脚本了. 自此开始, Qt脚本现在就叫javascript.
    不过作为土人, javascript中有一个prototype的概念, 现在才知道. javascript本没有类的概念, 跟不用说是继承之类的了. 但是凭借prototype的特性, 我们可以实现类似C++中类, 以及类继承等一些特性.
    prototype是个什么概念? 因为这个单词实在表意不清, 导致我花了很多时间来理解这个. 每个javascript对象都有一个指向另一个对象的引用, 这就是它的prototype. 一个对象的prototype定义了这个对象可以进行的操作集. 用C++来类比的话, 这些操作集是一定是成员函数. 看下面的javascript代码:

function Shape(x, y) {
    this.x = x;
    this.y = y;
}
Shape.prototype.area = function() { return 0; }

function Circle(x, y, radius) {
    Shape.call(this, x, y);
    this.radius = radius;
}
Circle.prototype = new Shape;
Circle.prototype.area = function() {
    return Math.PI * this.radius * this.radius;
}

function Shape(x, y) {

this.x = x;

this.y = y;

}

Shape.prototype.area = function() { return 0; }

function Circle(x, y, radius) {

Shape.call(this, x, y);

this.radius = radius;

}

Circle.prototype = new Shape;

Circle.prototype.area = function() {

return Math.PI * this.radius * this.radius;

}

我们把Circle对象的prototype设置成Shape对象, 实际上就是把Shape对象的prototype赋给了Circle对象, 让Circle对象的初始操作集跟Circle对象是一样的. 之后我们又重载了area()函数, 当然我们还可以加入新的函数. 它对应的C++代码如下:

class Shape
{
public:
    Shape(double x, double y) {
        this->x = x;
        this->y = y;
    }
    virtual double area() const { return 0; }
    double x;
    double y;
};

class Circle : public Shape
{
public:
    Circle(double x, double y, double radius) : Shape(x, y)
    {
        this->radius = radius;
    }
    double area() const { return M_PI * radius * radius; }
    double radius;
};

class Shape

{

public:

Shape(double x, double y) {

this->x = x;

this->y = y;

}

virtual double area() const { return 0; }

double x;

double y;

};

class Circle : public Shape

{

public:

Circle(double x, double y, double radius) : Shape(x, y)

{

this->radius = radius;

}

double area() const { return M_PI * radius * radius; }

double radius;

};

所以, 我们看到了, 对于一个javascript对象来说, 它还包括了一个内部的prototype对象. 对于Qt要用C++来实现类似prototype的功能的话, 除了要写一个javascript中的对应类, 还要写这个类对应的prototype类. 这个东西很高级, 也很麻烦, 所以建议看官方文档: http://doc.trolltech.com/4.3/qtscript.html#making-use-of-prototype-based-inheritance

下面我们来说一下一般怎样从Qt的C++代码中调用Qt的script代码. 假设我们要写一个dialog, 上面有一个QPushButton, 一个QLineEdit. 点击QPushButton的时候, 会弹出一个QMessageBox来显示消息.

a) 直接写Qt的C++代码的话, 只要用signal/slot就行了:

void HelloDialog::helloClicked()
{
    QString text = textEdit->text();
    text = "Hello " + text;
    QMessageBox::information(this, "info", text);
}

void HelloDialog::helloClicked()

{

QString text = textEdit->text();

text = "Hello " + text;

QMessageBox::information(this, "info", text);

}

b) 现在我们要加入javascript 的支持. 要解决的大概有这么一些问题: javascript中怎么拿到QLineEdit里的字符串? javascript中怎么调用QMessage这个Qt的类? 我们还是先来看代码:

QScriptValue constructQMessageBox(QScriptContext *, QScriptEngine *engine) {
    return engine->newQObject(new QMessageBox());
}

void HelloDialog::helloClicked()
{
    QString helloScript = scriptsDir.filePath("xxx.js");
    QFile file(helloScript);
    if (!file.open(QIODevice::ReadOnly)) {
        return;
    }
    QTextStream in(&file);
    in.setCodec("UTF-8");
    QString script = in.readAll();
    file.close();
    // section 1
    QScriptEngine engine;
    QScriptValue helloDialog = engine.newQObject(this);
    engine.globalObject().setProperty("helloDialog", helloDialog);
    // section 2
    QScriptValue constructor = engine.newFunction(constructQMessageBox);
    QScriptValue qsMetaObject = engine.newQMetaObject(&(QMessageBox::staticMetaObject), constructor);
    engine.globalObject().setProperty("QMessageBox", qsMetaObject);

    QScriptValue result = engine.evaluate(script);
}

QScriptValue constructQMessageBox(QScriptContext *, QScriptEngine *engine) {

return engine->newQObject(new QMessageBox());

}

void HelloDialog::helloClicked()

{

QString helloScript = scriptsDir.filePath("xxx.js");

QFile file(helloScript);

if (!file.open(QIODevice::ReadOnly)) {

return;

}

QTextStream in(&file);

in.setCodec("UTF-8");

QString script = in.readAll();

file.close();

// section 1

QScriptEngine engine;

QScriptValue helloDialog = engine.newQObject(this);

engine.globalObject().setProperty("helloDialog", helloDialog);

// section 2

QScriptValue constructor = engine.newFunction(constructQMessageBox);

QScriptValue qsMetaObject = engine.newQMetaObject(&(QMessageBox::staticMetaObject), constructor);

engine.globalObject().setProperty("QMessageBox", qsMetaObject);

QScriptValue result = engine.evaluate(script);

}

    我们先把整个javascript文件读进来, 加入一堆设置, 最后调用QScriptEngine::evaluate()函数来执行这段javascript. QScriptEngine这个类就相当于javascript的解释器.
    javascript里没有类这个概念, 所有的变量都是var类型. 如果要让Qt的C++类在javascript里运行, 那么先要将它包装(wrap)成一个javascript的类型. 代码的section 1部分把this(即当前的dialog)先做了包装, 然后把包装后的对象加入到javascript的运行环境的全局变量中.
    接着来解决QMessageBox的问题. 由于javascript中没有类, 继而也就是没构造函数这个概念, 但是当我们在javascript中new一个Qt C++对象的时候, 还是需要调用它的构造函数. 代码的section 2部分先把一个C++回调函数(之所以称为回调函数, 是因为要作为QScriptEngine::newFunction()的参数, signature是固定的)包装成一个QScriptValue, 然后把它和QMessageBox的meta-object信息一起包装成一个QScriptValue, 最后依样画葫芦地加入到javascript的运行环境的全局变量中. 这样我们就能在javascript中new出一个QMessageBox了.
    有一个很重要问题. 就是Qt的meta-object系统和javascript的调用系统是有对应关系的. 在javascript中, 一个var如果是QObject包装而来, 那么这个QObject的所有property(Q_PROPERTY声明), signal/slot都是可以在javascript中调用的. 还有就是这个QObject的所有child (指的是包含而不是继承关系), 也是可以直接访问的.
    看一下javascript代码. 其中greeting和text都是属性:

function showMessage(parent, title, text)
{
    var messageBox = new QMessageBox;
    messageBox.windowTitle = title;
    messageBox.text = text;
    messageBox.icon = QMessageBox.Information;
    return messageBox.exec();
}

return showMessage(helloDialog, "info", helloDialog.greeting + " " + helloDialog.text);

function showMessage(parent, title, text)

{

var messageBox = new QMessageBox;

messageBox.windowTitle = title;

messageBox.text = text;

messageBox.icon = QMessageBox.Information;

return messageBox.exec();

}

return showMessage(helloDialog, "info", helloDialog.greeting + " " + helloDialog.text);

c) 我们实现了用javascript来控制逻辑. GUI的话, Qt也提供了一种可以直接读取*.ui的方法: QUiLoader::load()函数. 于是我们连GUI也可以不用直接编译到binary里去了. 我们要做的就是用Qt的C++代码搭一个大概的框架, 加载需要的*.ui, *.js文件, 在适当的时候调用适当的javascript函数就行了. 而且*.ui文件对于每个控件都会有一个objectName的属性, 用uic生成代码的话, 这个值就是变量名, 如果用QUiLoader::load()的话, 这个就被赋给了QObject的objectName这个property. 当我们要在一个QWidget的javascript对象里引用它的子控件的时候, 便能直接用这个objectName来引用. 于是*.ui 和*.js文件可以说简直配合的天衣无缝那.
还是来看代码, Qt的C++代码没什么好说的, 就看javascript代码:

function showMessage(parent, title, text)
{
    var messageBox = new QMessageBox;
    messageBox.windowTitle = title;
    messageBox.text = text;
    messageBox.icon = QMessageBox.Information;
    return messageBox.exec();
}

function doClick()
{
    var text = dialog.textEdit.text;
    showMessage(dialog, "info", "Hello " + text);
}

dialog.show();
dialog.helloButton.clicked.connect(doClick);
return 0;

function showMessage(parent, title, text)

{

var messageBox = new QMessageBox;

messageBox.windowTitle = title;

messageBox.text = text;

messageBox.icon = QMessageBox.Information;

return messageBox.exec();

}

function doClick()

{

var text = dialog.textEdit.text;

showMessage(dialog, "info", "Hello " + text);

}

dialog.show();

dialog.helloButton.clicked.connect(doClick);

return 0;

直接访问子控件是不是清爽多了? 呵呵. 代码见这里. 其它请参考官方文档:
*) http://doc.trolltech.com/4.3/ecmascript.html
*) http://doc.trolltech.com/4.3/qtscript.html

Qt4学习笔记 (6)

January 22, 2015 by gonwan·0 Comments

This is a repost from my previous Qt learning series, based on Qt 4.3.

本篇继续介绍Qt的高级特性:

1. L&F Customization (自定义观感)

这个东西也就是传说中的skining, 换皮肤(画皮? – -). 如果你用过mfc或者java来实现控件的换肤功能的话, 那你一定觉得那是最恐怖的事情, 简直是一张张的图片往上贴啊… Qt也可以这么做, 但是提供了2种更聪明方便的方法:
a) qss (Qt Style Sheet): 这个东西灵感来源于html的css (书上也的是”inspired by”, 我就直译啦). 也就是说用qss来控制观感, 逻辑什么的还是用C++代码. 然后我就不介绍啦, 看看官方文档吧: http://doc.trolltech.com/4.3/stylesheet-syntax.html
b) 子类化QStyle类: Qt把所有观感相关的数据都抽象到了QStyle或者它的子类中, 我们要支持一个新的L&F的话, 只要继承这个类或者其子类, 重载一些函数就可以了. 这个我也不详细说啦, 书上也几乎都是抄的官方文档: http://doc.trolltech.com/4.3/style-reference.html

2. 插件框架:

    我们来想一下, 对于插件一般的实现方法. 能想到的大概是这样. 写一堆dll, 这些dll都提供统一的export接口函数.
    Qt的做法做法是差不多的, 只是在中间又提供了一层跨平台的抽象(shared dll在各个平台的实现都是不一样的嘛) 以及精简接口. 用PE Explorer可以看到所有的Qt plugin都只export了2个函数: qt_plugin_instance(), qt_plugin_query_verification_data(), 不过这两个函数具体是怎么调用的还没survey过.
    Qt的plugin可以分为两类: Qt本身的plugin和自己写的application的plugin.
    Qt的plugin可以implement 已有的接口. 比如可以implement QStylePlugin接口把style作为plugin, 可以implement QImageIOPlugin接口扩展Qt可以识别的图片格式, 等等. 这个就不说了.
    Qt的plugin还可以implement自定义的接口. 下面说一下大概的步骤:

a) 首先定义一个interface的类, 定义virtual functions, 最后调用Q_DECLARE_INTERFACE宏. 一般的interface都会提供这样的结构, 一个keys()接口说明当前plugin可以创建哪些object, 然后是一个创建object的函数(这里我写的doSomething()是同样的意思). 代码如下:

class QXxxInterface
{
public:
    virtual ~QXxxInterface() { }
    virtual QStringList keys() const = 0;
    virtual QXxx doSomething(QString key) = 0;
};
Q_DECLARE_INTERFACE(QXxxInterface, "com.ycool.gonwan.QXxxInterface/1.0")

class QXxxInterface

{

public:

virtual ~QXxxInterface() { }

virtual QStringList keys() const = 0;

virtual QXxx doSomething(QString key) = 0;

};

Q_DECLARE_INTERFACE(QXxxInterface, "com.ycool.gonwan.QXxxInterface/1.0")

b) Implement 这个interface, 以下分别是*.h文件和*.cpp文件:

// .h
class QMyXxxPlugin : public QObject, public QXxxInterface
{
    Q_OBJECT
    Q_INTERFACES(QXxxInterface)
public:
    QStringList keys() const;
    QXxx doSomething(QString key);
};[/code]
[code lang="cpp"][/code]// .cpp
Q_EXPORT_PLUGIN2(myxxxplugin, QMyXxxPlugin)

// .h

class QMyXxxPlugin : public QObject, public QXxxInterface

{

Q_OBJECT

Q_INTERFACES(QXxxInterface)

public:

QStringList keys() const;

QXxx doSomething(QString key);

};[/code]

[code lang="cpp"][/code]// .cpp

Q_EXPORT_PLUGIN2(myxxxplugin, QMyXxxPlugin)

*.h中的Q_INTERFACES宏用来告诉Qt的meta system这个类implement了哪个接口. 而*.cpp中Q_EXPORT_PLUGIN2宏是用来export dll接口的, 放在所有类成员函数之外调用就行了.

c) 调用, Qt提供了一个QPluginLoader类专门用来load插件. 依据上面现有的代码, 我们可以如下调用:

QPluginLoader loader("./plugins/myxxxplugin.dll");
if (QXxxInterface *interface = qobject_cast<QXxxInterface *>(loader.instance()))
{
    foreach (QString key, interface.keys())
    {
        interface.doSomething(key);
    }
}

QPluginLoader loader("./plugins/myxxxplugin.dll");

if (QXxxInterface *interface = qobject_cast<QXxxInterface *>(loader.instance()))

{

foreach (QString key, interface.keys())

{

interface.doSomething(key);

}

以上代码并不涉及具体的plugin的操作, 否则就不能叫做plugin了呵呵.
官方文档: http://doc.trolltech.com/4.3/plugins-howto.html

Qt4学习笔记 (5)

January 22, 2015 by gonwan·0 Comments

This is a repost from my previous Qt learning series, based on Qt 4.3.

本篇说一下Qt所谓的高级特性: i18n 的支持 (Internationalization).
首先明确一点, Qt对于unicode的支持是相当好的, 用来表示字符串的QString保存的是16-bit的QChar(官方文档上这么写哦), 跟java的char是一样的. 但是但是..实际上QString的内部数据一点也没有用到QChar, 大概是为了performance的考虑不吧, 附一段源码(/src/corelib/tools/qstring.h):

struct Data {
    QBasicAtomic ref;
    int alloc, size;
    ushort *data;
    ushort clean : 1;
    ushort simpletext : 1;
    ushort righttoleft : 1;
    ushort asciiCache : 1;
    ushort capacity : 1;
    ushort reserved : 11;
    ushort array[1];
};
Data *d;

struct Data {

QBasicAtomic ref;

int alloc, size;

ushort *data;

ushort clean : 1;

ushort simpletext : 1;

ushort righttoleft : 1;

ushort asciiCache : 1;

ushort capacity : 1;

ushort reserved : 11;

ushort array[1];

};

Data *d;

大概是这么个情况. 下面来说一下怎么样支持i18n.

a) 首先要做的就是把要翻译的string统统用tr()函数包起来(其实是QObject::tr()). 当然还有其它的方法, 不过这个最容易.

b) 编辑*.pro文件, 加入需要支持的语言信息. 比如我们要支持简体中文和日本语:

TRANSLATIONS  = find_zh.ts \
                find_ja.ts

1 2	TRANSLATIONS = find_zh.ts \ find_ja.ts

c) 运行lupdate来生成上面两个*.ts文件. lupdate会自动搜索需要翻译的字符串(用tr()函数包起来的作用):

# lupdate -verbose find.pro

1	# lupdate -verbose find.pro

d) 用Qt linguist来编辑生成的两个文件, 当然如果你够nb.. 可以手动编辑… 截张图:

e) 嗯.. 最好是全部都打勾了才好.. 工具栏上有检查选项, 通过了才打勾. 接着就是运行lrelease工具把*.ts文件转成binary的*.qm文件, 以便可以添加到Qt的resource文件(*.qrc) 中使用:

# lrelease -verbose find.pro

1	# lrelease -verbose find.pro

f) 新加一个*.qrc资源文件, 内容如下. 具体语法请查阅官方文档:

<RCC>
    <qresource prefix="/translations" >
        <file>find_ja.qm</file>
        <file>find_zh.qm</file>
    </qresource>
</RCC>

<RCC>

</qresource>

</RCC>

g) 然后就一切正常了:

# qmake find.pro
# nmake

1 2	# qmake find.pro # nmake

h) 代码里大概可以这样写, 就是对QApplication对象设一个translation的属性类, 注释可以用来切换语言:

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QTranslator appTranslator;
    appTranslator.load("find_" + QLocale::system().name(), ":/translations");
    //appTranslator.load("find_zh.qm", ":/translations");
    //appTranslator.load("find_ja.qm", ":/translations");
    app.installTranslator(&appTranslator);
    FindDialog *dialog = new FindDialog;
    dialog->show();
    return app.exec();
}

int main(int argc, char *argv[])

{

QApplication app(argc, argv);

QTranslator appTranslator;

appTranslator.load("find_" + QLocale::system().name(), ":/translations");

//appTranslator.load("find_zh.qm", ":/translations");

//appTranslator.load("find_ja.qm", ":/translations");

app.installTranslator(&appTranslator);

FindDialog *dialog = new FindDialog;

dialog->show();

return app.exec();

}

还是截张图吧..三种语言…:

可以看到, Qt的layout又发挥作用了, 中文和日文的dialog相对长了一些.

以上. 代码见这里.