使用jackson来实现json和object之间转换。
使用的时候在resultMap中，对应的列配置，例如：
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| <result column="specs" property="specs"
typeHandler="cn.devmgr.tutorial.typehandler.JsonTypeHandler" />
|
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| update table_xxx
set colA=#{beanA.xxx, typeHandler=cn.devmgr.tutorial.typehandler.JsonTypeHandler}
where id=xx
|
JsonTypeHandler.java
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| package cn.devmgr.tutorial.typehandler;
import java.io.IOException;
import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
public class JsonTypeHandler<T> extends BaseTypeHandler<T> {
private final static Log log = LogFactory.getLog(JsonTypeHandler.class);
private static ObjectMapper objectMapper;
private Class<T> type;
static {
objectMapper = new ObjectMapper();
}
public JsonTypeHandler(Class<T> type) {
if(log.isTraceEnabled()) {
log.trace("JsonTypeHandler(" + type + ")");
}
if (type == null) {
throw new IllegalArgumentException("Type argument cannot be null");
}
this.type = type;
}
private T parse(String json) {
try {
if(json == null || json.length() == 0) {
return null;
}
return objectMapper.readValue(json, type);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
private String toJsonString(Object obj) {
try {
return objectMapper.writeValueAsString(obj);
} catch (JsonProcessingException e) {
throw new RuntimeException(e);
}
}
@Override
public T getNullableResult(ResultSet rs, String columnName) throws SQLException {
return (T) parse(rs.getString(columnName));
}
@Override
public T getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
return (T) parse(rs.getString(columnIndex));
}
@Override
public T getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
return (T) parse(cs.getString(columnIndex));
}
@Override
public void setNonNullParameter(PreparedStatement ps, int columnIndex, T parameter, JdbcType jdbcType) throws SQLException {
ps.setString(columnIndex, toJsonString(parameter));
}
}
|