ORACLE驱动thin方式动态切换客户端字符集实现

表里明明有这条数据，SQL语句却查不到？
A客户端写入，B查询出来的内容却是乱码？
在未知数据编码的情况下如何做到动态的切换客户端字符集去适应变化？

SELECT * FROM NLS_DATABASE_PARAMETERS;  //查看数据库端NLS相关设置

SELECT USERENV('language') FROM DUAL;//查看用户session级别的设置

SELECT * FROM V$NLS_PARAMETERS;

user.language

NLS_LANGUAGE

NLS_TERRITORY

file.encoding

US7ASCII

WE8ISO8859P1

UCS-2

UCS-2

public static final byte[] stringToASCII(String var0) {
byte[] var1 = new byte[var0.length()];
var1 = var0.getBytes();
return var1;
}

/**
* oracle.jdbc.driver.DBConversion 转换bytes的入口
**/
public byte[] StringToCharBytes(String var1) throws SQLException {
if(var1.length() == 0) {
return null;
} else {
switch(this.clientCharSetId) {
case -1:
return this.serverCharSet.convertWithReplacement(var1);
case 2:
case 31:
case 178:
return this.clientCharSet.convertWithReplacement(var1);
default:
return stringToDriverCharBytes(var1, this.clientCharSetId);
}
}
}

<dependency>
<groupId>oracle.i18n</groupId>
<artifactId>orai18n</artifactId>
<version>12.1.0</version>
</dependency>

//设置prepareStatement代理
OraclePreparedStatementProxy proxy=new OraclePreparedStatementProxy(statement,targetCharacterType);
PreparedStatement proxyStatement = (PreparedStatement) Proxy.newProxyInstance(statement.getClass().getClassLoader(), new Class[]{PreparedStatement.class}, proxy);
//使用代理获取结果
ResultSet resultSet = proxyStatement.executeQuery();

import com.xxx.CharacterType;
import oracle.jdbc.OraclePreparedStatement;
import oracle.sql.CharacterSet;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.sql.PreparedStatement;

/**
* Created by.
* 类说明：代理
*/
public class OraclePreparedStatementProxy implements InvocationHandler {

private static final Log logger = LogFactory.getLog(OraclePreparedStatementProxy.class);

private PreparedStatement target;

private CharacterType characterType;

private Object clientCharSetIdTmp;

private Object clientCharSetTmp;

private Object conversionField;

public OraclePreparedStatementProxy(PreparedStatement target, CharacterType characterType) {
this.target = target;
this.characterType = characterType;
}

@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
try {
if (method.getName().equals("executeQuery")||method.getName().equals("executeUpdate")||method.getName().equals("close")) {
if (target instanceof OraclePreparedStatement){
if (method.getName().equals("close")){//上下文依赖 清除设置
filterStatementCharacterSet(target,characterType,Boolean.FALSE);
}else {
filterStatementCharacterSet(target,characterType,Boolean.TRUE);
}
return method.invoke(target, args);

}
}
return method.invoke(target, args);
} catch (Exception e) {
if (e.getCause() == null) {
throw e;
} else {
throw e.getCause();
}
}
}

/**
* 由于oracle驱动无法直接设置编码 且底层使用getBytes()将数据流传给db，严重依赖运行环境的编码
* 在这里指定客户端编码来解决
* @param oraclePreparedStatement
*/
private void filterStatementCharacterSet(Object oraclePreparedStatement, CharacterType characterType,boolean isGet){
try {
if (null==characterType||characterType==CharacterType.UNKNOWN){
return;
}
CharacterSet characterSet;
switch (characterType){
case UTF8:
case UTF_8:
characterSet=CharacterSet.make(CharacterSet.UTF8_CHARSET);
break;
case GB2312:
case ISO8859_1:
case ISO_8859_1:
case GBK:
characterSet=CharacterSet.make(CharacterSet.ZHS16GBK_CHARSET);
break;
default:
return;
}
Class<?> c;
if (isGet){
c = Class.forName("oracle.jdbc.driver.OraclePreparedStatementWrapper");
Field preparedStatement = c.getDeclaredField("preparedStatement");
preparedStatement.setAccessible(true);
Object t4CPreparedStatement = preparedStatement.get(oraclePreparedStatement);

c = Class.forName("oracle.jdbc.driver.OracleStatement");
Field sqlObject = c.getDeclaredField("sqlObject");
sqlObject.setAccessible(true);
Object sqlObjectField = sqlObject.get(t4CPreparedStatement);

c = Class.forName("oracle.jdbc.driver.OracleSql");
Field conversion = c.getDeclaredField("conversion");
conversion.setAccessible(true);
conversionField = conversion.get(sqlObjectField);
}
c = Class.forName("oracle.jdbc.driver.DBConversion");
Field clientCharSetId = c.getDeclaredField("clientCharSetId");
clientCharSetId.setAccessible(true);

if (isGet){
//设置开启客户端编码
clientCharSetIdTmp=clientCharSetId.get(conversionField);
clientCharSetId.setShort(conversionField, (short) 2);
}else {
clientCharSetId.set(conversionField, clientCharSetIdTmp);
}

Field clientCharSet = c.getDeclaredField("clientCharSet");
clientCharSet.setAccessible(true);
if (isGet){
//设置客户端编码
clientCharSetTmp=clientCharSet.get(conversionField);
clientCharSet.set(conversionField, characterSet);
}else {
clientCharSet.set(conversionField, clientCharSetTmp);
}
} catch (Exception e) {
logger.error("filterStatementCharacterSet error!",e);
}

}

}