我有一些复杂的查询要使用一些可选的过滤器来构建，MyBatis 似乎是生成动态 SQL 的理想候选者。
但是，我仍然希望我的查询在与应用程序的其余部分（不使用 MyBatis）相同的框架中执行。
所以我希望做的是严格使用 MyBatis 来生成 SQL，但从那里使用我的应用程序的其余部分来实际执行它。这可能吗？如果是这样，怎么做？
问问题
16163 次
5 回答
15
虽然 MyBatis 被设计为在构建后执行查询，但您可以利用它的配置和一点“内部知识”来获得您需要的内容。
MyBatis 是一个非常好的框架，不幸的是它在文档方面缺乏，所以源代码是你的朋友。如果您仔细研究，您应该会遇到这些类：org.apache.ibatis.mapping.MappedStatement它们org.apache.ibatis.mapping.BoundSql是构建动态 SQL 的关键参与者。这是一个基本的使用示例：
user包含此数据的MySQL 表：
name login
----- -----
Andy a
Barry b
Cris c
User班级：
package pack.test;
public class User {
private String name;
private String login;
// getters and setters ommited
}
UserService界面：
package pack.test;
public interface UserService {
// using a different sort of parameter to show some dynamic SQL
public User getUser(int loginNumber);
}
UserService.xml映射器文件：
<mapper namespace="pack.test.UserService">
<select id="getUser" resultType="pack.test.User" parameterType="int">
<!-- dynamic change of parameter from int index to login string -->
select * from user where login = <choose>
<when test="_parameter == 1">'a'</when>
<when test="_parameter == 2">'b'</when>
<otherwise>'c'</otherwise>
</choose>
</select>
</mapper>
sqlmap-config.file：
<configuration>
<settings>
<setting name="lazyLoadingEnabled" value="false" />
</settings>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost/test"/>
<property name="username" value="..."/>
<property name="password" value="..."/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="pack/test/UserService.xml"/>
</mappers>
</configuration>
AppTester显示结果：
package pack.test;
import java.io.Reader;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
public class AppTester {
private static String CONFIGURATION_FILE = "sqlmap-config.xml";
public static void main(String[] args) throws Exception {
Reader reader = null;
SqlSession session = null;
try {
reader = Resources.getResourceAsReader(CONFIGURATION_FILE);
session = new SqlSessionFactoryBuilder().build(reader).openSession();
UserService userService = session.getMapper(UserService.class);
// three users retreived from index
for (int i = 1; i <= 3; i++) {
User user = userService.getUser(i);
System.out.println("Retreived user: " + user.getName() + " " + user.getLogin());
// must mimic the internal statement key for the mapper and method you are calling
MappedStatement ms = session.getConfiguration().getMappedStatement(UserService.class.getName() + ".getUser");
BoundSql boundSql = ms.getBoundSql(i); // parameter for the SQL statement
System.out.println("SQL used: " + boundSql.getSql());
System.out.println();
}
} finally {
if (reader != null) {
reader.close();
}
if (session != null) {
session.close();
}
}
}
}
结果：
Retreived user: Andy a
SQL used: select * from user where login = 'a'
Retreived user: Barry b
SQL used: select * from user where login = 'b'
Retreived user: Cris c
SQL used: select * from user where login = 'c'
于 2012-11-04T18:00:41.313 回答
3
大家都知道如何使用BoundSql.getSql()从MyBatis获取参数化查询字符串，像这样：
// get parameterized query
MappedStatement ms = configuration.getMappedStatement("MyMappedStatementId");
BoundSql boundSql = ms.getBoundSql(parameters);
System.out.println("SQL" + boundSql.getSql());
// SELECT species FROM animal WHERE name IN (?, ?) or id = ?
但现在您需要等式的另一半，即与问号对应的值列表：
// get parameters
List<ParameterMapping> boundParams = boundSql.getParameterMappings();
String paramString = "";
for(ParameterMapping param : boundParams) {
paramString += boundSql.getAdditionalParameter(param.getProperty()) + ";";
}
System.out.println("params:" + paramString);
// "Spot;Fluffy;42;"
现在，您可以将其序列化以发送到其他地方以运行，或者您可以将其打印到日志中，这样您就可以将它们拼接在一起并手动运行查询。
*代码未经测试，可能是次要类型问题或类似问题
于 2016-12-08T17:08:36.767 回答
1
mybatis版本是3.4.5
实用类
要将mapper转换为sql，需要mapper接口类、方法名、参数和sqlSession。
package util;
import java.lang.reflect.Method;
import java.text.DateFormat;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import java.util.regex.Matcher;
import org.apache.ibatis.binding.MapperMethod.MethodSignature;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.ParameterMapping;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.type.TypeHandlerRegistry;
import org.springframework.util.CollectionUtils;
/**
* @author zwxbest - 19-4-25
*/
public class SqlUtil {
public static String showSql(SqlSession sqlSession, Class mapperInterface, String methodName,
Object[] params) {
Configuration configuration = sqlSession.getConfiguration();
MappedStatement ms = configuration.getMappedStatement(
mapperInterface.getName() + "." + methodName);
Method sqlMethod = null;
//find method equals methodName
for (Method method : mapperInterface.getDeclaredMethods()) {
if (method.getName().equals(methodName)) {
sqlMethod = method;
break;
}
}
if (sqlMethod == null) {
throw new RuntimeException("mapper method is not found");
}
MethodSignature method = new MethodSignature(configuration, mapperInterface, sqlMethod);
Object paramObject = method.convertArgsToSqlCommandParam(params);
BoundSql boundSql = ms.getBoundSql(paramObject);
Object parameterObject = boundSql.getParameterObject();
List<ParameterMapping> parameterMappings = boundSql
.getParameterMappings();
String sql = boundSql.getSql().replaceAll("[\\s]+", " ");
if (!CollectionUtils.isEmpty(parameterMappings) && parameterObject != null) {
TypeHandlerRegistry typeHandlerRegistry = configuration
.getTypeHandlerRegistry();
if (typeHandlerRegistry.hasTypeHandler(parameterObject.getClass())) {
sql = sql.replaceFirst("\\?",
Matcher.quoteReplacement(getParameterValue(parameterObject)));
} else {
MetaObject metaObject = configuration.newMetaObject(
parameterObject);
for (ParameterMapping parameterMapping : parameterMappings) {
String propertyName = parameterMapping.getProperty();
if (metaObject.hasGetter(propertyName)) {
Object obj = metaObject.getValue(propertyName);
sql = sql
.replaceFirst("\\?", Matcher.quoteReplacement(getParameterValue(obj)));
} else if (boundSql.hasAdditionalParameter(propertyName)) {
Object obj = boundSql.getAdditionalParameter(propertyName);
sql = sql
.replaceFirst("\\?", Matcher.quoteReplacement(getParameterValue(obj)));
} else {
sql = sql.replaceFirst("\\?", "missing");
}
}
}
}
return sql;
}
/**
* if param's type is `String`,add single quotation<br>
*
* if param's type is `datetime`,convert to string and quote <br>
*/
private static String getParameterValue(Object obj) {
String value = null;
if (obj instanceof String) {
value = "'" + obj.toString() + "'";
} else if (obj instanceof Date) {
DateFormat formatter = DateFormat
.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT, Locale.CHINA);
value = "'" + formatter.format(new Date()) + "'";
} else if (obj instanceof LocalDateTime) {
value = "\'" + ((LocalDateTime) obj)
.format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")) + "\'";
} else {
if (obj != null) {
value = obj.toString();
} else {
value = "";
}
}
return value;
}
}
调用示例
sqlSession 由 Spring 注入。
@Autowired
private SqlSession sqlSession;
String sql = SqlUtil
.showSql(sqlSession, PromotionCodeMapper.class, "selectByPromotionCodeForUpdate",
new Object[]{"111"});
log.warn(sql);
于 2019-04-25T06:32:24.063 回答
0
getBoundSql()只是添加到 Bogdan 的正确答案：如果您的接口具有更复杂的签名，则需要将 JavaBean 传递给带有 getter 的接口参数。
假设您要根据登录号和/或用户名查询用户。您的界面可能如下所示：
package pack.test;
public interface UserService {
// using a different sort of parameter to show some dynamic SQL
public User getUser(@Param("number") int loginNumber, @Param("name") String name);
}
我省略了 Mapper 代码，因为它与本次讨论无关，但您在 AppTester 中的代码应变为：
[...]
final String name = "Andy";
User user = userService.getUser(i, name);
System.out.println("Retreived user: " + user.getName() + " " + user.getLogin());
// must mimic the internal statement key for the mapper and method you are calling
MappedStatement ms = session.getConfiguration().getMappedStatement(UserService.class.getName() + ".getUser");
BoundSql boundSql = ms.getBoundSql(new Object() {
// provide getters matching the @Param's in the interface declaration
public Object getNumber() {
return i;
}
public Object getName() {
return name;
}
});
System.out.println("SQL used: " + boundSql.getSql());
System.out.println();
[...]
于 2014-01-21T14:50:16.213 回答
0
public static void main(String[] args) throws Exception {
String script = "<script>select * from table where 1 = 1<if test='id != null'>and id = ${id} </if></script>";
System.out.println(buildSql(script));
}
private static String buildSql(String script) {
LanguageDriver languageDriver = new XMLLanguageDriver();
Configuration configuration = new Configuration();
SqlSource sqlSource = languageDriver.createSqlSource(configuration, script, Object.class);
Map<String, String> parameters = new HashMap<>();
parameters.put("id", "1");
BoundSql boundSql = sqlSource.getBoundSql(parameters);
return boundSql.getSql();
}
使用 ${id} 而不是 #{id}
结果是： select * from table where 1 = 1 and id = 1
于 2021-08-19T06:09:02.813 回答