如何通过JDBC接口将UTF-8字符串正确写入MySQL [英] How to correctly write UTF-8 strings into MySQL through JDBC interface

问题描述

连接数据库:

public DBSource(ConnectionInfo ci) throws
        ClassNotFoundException, InstantiationException,
        IllegalAccessException, SQLException
{
    Class.forName("com.mysql.jdbc.Driver").newInstance();
    String dbPath = String.format(
        "jdbc:mysql://%s:%d/%s?user=%s&password=%s&characterEncoding=utf-8&" + 
        "useUnicode=true", ci.host, ci.port, ci.dbName, ci.user, ci.password);
    conn = java.sql.DriverManager.getConnection(dbPath);
    prepareTables();
}

表创建代码:

private void prepareTables() throws SQLException
{
    java.sql.Statement stat = conn.createStatement();

    String query = "set names utf8";
    stat.execute(query);

    query = "set character set utf8";
    stat.execute(query);

    query = "show variables like '%char%'";
    stat.execute(query);
    java.sql.ResultSet rs = stat.getResultSet();
    while (rs.next())
    {
        String k = rs.getString(1);
        String v = rs.getString(2);
        System.out.println(k + " - " + v);
    }
    
    query = "drop table if exists clt";
    stat.execute(query);
    query = "create table clt"
            + "("
            + "  id bigint not null"
            + ", text varchar(50) not null"
            + ") default character set utf8";
    stat.execute(query);
}

行插入:

public void visit(Insert i) throws SQLException
{
    String query = "insert into clt"
            + " (id, text) values (?, ?)";
    java.sql.PreparedStatement stmt = conn.prepareStatement(query);
    if (i.rowData.id == 12656697)
    {
        String toOut = "<<< " + Long.toString(i.rowData.id) + " - " + i.rowData.text;
        System.out.println(toOut);
    }
    int it = 0;
    stmt.setLong(++it, i.rowData.id);
    stmt.setString(++it, i.rowData.text);
    stmt.execute();
    stmt.close();
}

检查数据:

 public void checkText() throws SQLException
{
    java.sql.Statement stmt = conn.createStatement();
    String query = "select id, text from clt where id = '12656697'";
    stmt.execute(query);
    java.sql.ResultSet rs = stmt.getResultSet();
    while (rs.next())
    {
        String k = rs.getString(1);
        String v = rs.getString(2);
        String toOut = ">>> " + k + " - " + v;
        System.out.println(toOut);
    }
}

输出:

character_set_client - utf8
character_set_connection - latin1
character_set_database - latin1
character_set_filesystem - binary
character_set_results - utf8
character_set_server - utf8
character_set_system - utf8
character_sets_dir - /usr/share/mysql/charsets/

<<< 12656697 - Апарати
>>> 12656697 - ???????

问题:在表中我有?????????????"文本字段中的符号.

Problem: In table I have "???????????" symbols at the text field.

期望的字符串是:Апарати
结果:???????

这是某种魔法?

我解决了一个问题......但如果有人能向我解释它仍然会很感激.

I resolved an issue... But still will appreciate if somebody can explain it to me.

所以.

1. 我添加了由 Costis Aivalis 建议的/etc/mysql/my.cnf 行
   结果一样
2. 我从代码中删除了几行:
   query = "set character set utf8";
   stat.execute(query);

它正在工作！！！:)

推荐答案

确保您的 MySQL 配置编码被正确定义.使用以下命令检查您的设置和修改的正确性:

Ensure that your MySQL configuration encoding is defined correctly. Check your settings and the correctness of the modifications with these commands:

show variables like 'character%';

和 显示变量，如 'collat​​ion%';

将这些行添加到 my.cnf 或 my.ini:

Add these lines to either my.cnf or my.ini:

对于 MySQL 5.1.nn 和更高版本 5.5.29，您只需要这两行:

For MySQL 5.1.nn, and later versions 5.5.29 you just need these two lines:

[mysqld]
character-set-server = utf8
character-set-filesystem = utf8

对于 MySQL 5.0.nn 及更早版本，请使用以下设置:

For MySQL 5.0.nn and older use these settings:

[client]
default-character-set=utf8

[mysql]
default-character-set=utf8

[mysqld]
default-character-set=utf8
character-set-server=utf8

使用 MySQL-Workbench 进行设置可能更方便.5+ 版本非常好.

It is probably more convenient to use MySQL-Workbench for your settings. Versions 5+ are excellent.

在你的 Java 程序中像这样连接:

In your Java program connect like this:

con = DriverManager.getConnection("jdbc:mysql://localhost:3306/myDatabase?useUnicode=true&characterEncoding=UTF-8","user","passwd");

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