ibatis 中blob的使用

最新推荐文章于 2021-03-19 05:38:08 发布

MuuMo

最新推荐文章于 2021-03-19 05:38:08 发布

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分类专栏：学习笔记文章标签： ibatis blob

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本文介绍了一个自定义的MyBatis Blob类型处理器，用于处理字符串与Blob类型的转换。该处理器实现了BaseTypeHandler接口，提供了将字符串转换为Blob类型及从Blob类型还原字符串的方法。

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import java.io.ByteArrayInputStream;
import java.io.UnsupportedEncodingException;
import java.sql.Blob;
import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;


public class MyBlobTypeHandler extends BaseTypeHandler<String>{
    private static final String DEFAULT_CHARSET = "utf-8";

    @Override
    public void setNonNullParameter(PreparedStatement ps, int i,
                                    String parameter, JdbcType jdbcType) throws SQLException {
        ByteArrayInputStream bis;
        try {
            //把String转化成byte流
            bis = new ByteArrayInputStream(parameter.getBytes(DEFAULT_CHARSET));
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException("Blob Encoding Error!");
        }
        ps.setBinaryStream(i, bis, parameter.length());
    }

    @Override
    public String getNullableResult(ResultSet rs, String columnName)
            throws SQLException {
        Blob blob = rs.getBlob(columnName);
        byte[] returnValue = null;
        if (null != blob) {
            returnValue = blob.getBytes(1, (int) blob.length());
        }
        try {
            //把byte转化成string
            return new String(returnValue, DEFAULT_CHARSET);
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException("Blob Encoding Error!");
        }
    }

    @Override
    public String getNullableResult(CallableStatement cs, int columnIndex)
            throws SQLException {
        Blob blob = cs.getBlob(columnIndex);
        byte[] returnValue = null;
        if (null != blob) {
            returnValue = blob.getBytes(1, (int) blob.length());
        }
        try {
            return new String(returnValue, DEFAULT_CHARSET);
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException("Blob Encoding Error!");
        }
    }

    @Override
    public String getNullableResult(ResultSet rs, int index) throws SQLException
    {
        Blob blob = rs.getBlob(index);
        byte[] returnValue = null;
        if (null != blob) {
            returnValue = blob.getBytes(1, (int) blob.length());
        }
        try {
            //把byte转化成string
            return new String(returnValue, DEFAULT_CHARSET);
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException("Blob Encoding Error!");
        }
    }
}

在xml文件中修改

<result column="CONTENT" property="content" jdbcType="BLOB" typeHandler="com.***.utils.MyBlobTypeHandler"/>