Mybatis基于注解形式的sql语句生成实例代码

对其做了些优化，但此种sql生成方式仅适用于复杂程度不高的sql，所以实用性不是很高，仅仅是写着玩的，知道点mybatis的注解形式的使用方式，可能以后会逐渐完善起来。第一次写博客，写的简单点。

package com.bob.config.mvc.mybatis;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* 实体类对应的列
*
* @author jjb
* @create 2017-09-08 14:42
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD, ElementType.METHOD})
public @interface Column {
 /**
  * 当前属性对应的列名
  *
  * @return
  */
 String value() default "";
 /**
  * 当前属性是不是表必须的
  *
  * @return
  */
 boolean required() default true;
}

package com.bob.config.mvc.mybatis;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* 实体类对应的表
*
* @author jjb
* @create 2017-09-08 14:44
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE})
public @interface Table {
 String value() default "";
 /**
  * 当前表的主键
  *
  * @return
  */
 String key();
}

package com.bob.config.mvc.mybatis;
import org.apache.ibatis.annotations.DeleteProvider;
import org.apache.ibatis.annotations.InsertProvider;
import org.apache.ibatis.annotations.Options;
import org.apache.ibatis.annotations.SelectProvider;
import org.apache.ibatis.annotations.UpdateProvider;
/**
* Mybatis基础Mapper
*
* @author jjb
* @create 2017-09-08 14:37
*/
public interface BaseMapper<T> {
 /**
  * 插入语句
  *
  * @param bean
  * @return
  */
 @Options(useGeneratedKeys = true)
 @InsertProvider(type = SqlProvider.class, method = "insert")
 public int insert(T bean);
 /**
  * 删除语句
  *
  * @param bean
  * @return
  */
 @DeleteProvider(type = SqlProvider.class, method = "delete")
 public int delete(T bean);
 /**
  * 更新语句
  *
  * @param bean
  * @return
  */
 @UpdateProvider(type = SqlProvider.class, method = "update")
 public int update(T bean);
 /**
  * 查找语句
  *
  * @param bean
  * @return
  */
 @SelectProvider(type = SqlProvider.class, method = "select")
 public T findFirst(T bean);
}

package com.bob.config.mvc.mybatis;
import java.time.LocalDate;
/**
* Mybatis实体类
*
* @author jjb
* @create 2017-09-08 17:16
*/
@Table(key = "id")
public class MybatisEntity {
 @Column()
 private String id;
 @Column("USER_NAME")
 private String name;
 @Column()
 private Integer age;
 private LocalDate date;
 @Column("ADRESS_NUMBER")
 private Integer userAdressNumber;
 public String getId() {
   return id;
 }
 public void setId(String id) {
   this.id = id;
 }
 public String getName() {
   return name;
 }
 public void setName(String name) {
   this.name = name;
 }
 public Integer getAge() {
   return age;
 }
 public void setAge(Integer age) {
   this.age = age;
 }
 @Column("CUR_DATE")
 public LocalDate getDate() {
   return date;
 }
 public void setDate(LocalDate date) {
   this.date = date;
 }
 public Integer getUserAdressNumber() {
   return userAdressNumber;
 }
 public void setUserAdressNumber(Integer userAdressNumber) {
   this.userAdressNumber = userAdressNumber;
 }
}

package com.bob.config.mvc.mybatis;
import java.lang.reflect.Field;
import java.util.Map;
/**
* 表到实体的格式化器
*
* @author jjb
* @create 2017-09-08 14:51
*/
public interface TableFormatter {
 /**
  * 根据属性获取字段名称
  *
  * @param field
  * @return
  */
 public String getColumnName(Field field);
 /**
  * 获取主键属性对应的列名
  *
  * @return
  */
 public String getKeyColumnName(Class<?> clazz);
 /**
  * 获取主键的属性名称
  *
  * @param clazz
  * @return
  */
 public String getKeyFiledName(Class<?> clazz);
 /**
  * 根据类获取表名称
  *
  * @param clazz
  * @return
  */
 public String getTableName(Class<?> clazz);
 /**
  * 获取一个类的所有属性的映射信息
  *
  * @param clazz
  * @return
  */
 public Map<Field, String> getFieldMappings(Class<?> clazz);
}

package com.bob.config.mvc.mybatis;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.Map;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeanUtils;
import org.springframework.stereotype.Component;
import org.springframework.util.Assert;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.StringUtils;
/**
* 依据驼峰原则来将表的信息格式化为实体类的信息，在驼峰处改小写同时插入下划线
*
* @author jjb
* @create 2017-09-08 14:55
*/
@Component
public class HumpToUnderLineFormatter implements TableFormatter {
 private static final Logger LOGGER = LoggerFactory.getLogger(HumpToUnderLineFormatter.class);
 private static final Map<Class<?>, Map<Field, String>> FIELD_TO_COLUMN_MAPPINGS = new HashMap<Class<?>, Map<Field, String>>();
 private static final Map<Class, String> CLASS_TO_TABLE_MAPPING = new HashMap<Class, String>();
 private static final StringBuilder SB = new StringBuilder();
 private static final Object LOCK = new Object();
 @Override
 public String getColumnName(Field field) {
   Assert.notNull(field, "属性不能为空");
   Map<Field, String> mappings = FIELD_TO_COLUMN_MAPPINGS.get(field.getDeclaringClass());
   if (mappings == null) {
     synchronized (LOCK) {
       mappings = FIELD_TO_COLUMN_MAPPINGS.get(field.getDeclaringClass());
       if (mappings == null) {
         mappings = buildMapping(field.getDeclaringClass());
       }
     }
   }
   return mappings.get(field);
 }
 @Override
 public String getKeyColumnName(Class<?> clazz) {
   Table table = checkClass(clazz);
   return getColumnName(ReflectionUtils.findField(clazz,table.key()));
 }
 @Override
 public String getKeyFiledName(Class<?> clazz) {
   Table table = checkClass(clazz);
   Field field = ReflectionUtils.findField(clazz,table.key());
   Assert.state(field != null,"@Table的key()指定的属性必须存在");
   return field.getName();
 }
 private Table checkClass(Class<?> clazz){
   Assert.isTrue(clazz != null , "与Table对应的Class不能为空");
   Table table = clazz.getAnnotation(Table.class);
   Assert.isTrue(table != null && StringUtils.hasText(table.key()),"["+clazz.getName()+"]必须标识@Table注解且key()不能为空");
   return table;
 }
 @Override
 public String getTableName(Class<?> clazz) {
   Assert.notNull(clazz, "类不能为空");
   Assert.isTrue(clazz.isAnnotationPresent(Table.class), "[" + clazz.getName() + "]类上必须含有@Table注解");
   String name = CLASS_TO_TABLE_MAPPING.get(clazz);
   if (name == null) {
     synchronized (LOCK) {
       name = CLASS_TO_TABLE_MAPPING.get(clazz);
       if (name == null) {
         buildMapping(clazz);
       }
     }
   }
   return CLASS_TO_TABLE_MAPPING.get(clazz);
 }
 @Override
 public Map<Field, String> getFieldMappings(Class<?> clazz) {
   Assert.isTrue(clazz != null && clazz.isAnnotationPresent(Table.class), "与Table对应的Class不能为空且必须标识@Table注解");
   Map<Field, String> mappings = FIELD_TO_COLUMN_MAPPINGS.get(clazz);
   if (mappings == null) {
     synchronized (LOCK) {
       mappings = FIELD_TO_COLUMN_MAPPINGS.get(clazz);
       if (mappings == null) {
         mappings = buildMapping(clazz);
       }
     }
   }
   return FIELD_TO_COLUMN_MAPPINGS.get(clazz);
 }
 /**
  * 创建实体到表映射
  *
  * @param clazz
  */
 private Map<Field, String> buildMapping(Class<?> clazz) {
   buildClassToTableMapping(clazz);
   Map<Field, String> mappings = new HashMap<Field, String>();
   FIELD_TO_COLUMN_MAPPINGS.put(clazz, mappings);
   buildFiledToColumnMapping(clazz, mappings);
   buildFiledToColumnMappingWithGetter(clazz, mappings);
   return mappings;
 }
 /**
  * 创建类名到表名的名称映射
  *
  * @param clazz
  */
 private void buildClassToTableMapping(Class<?> clazz) {
   Table table = clazz.getAnnotation(Table.class);
   Assert.notNull(table, "[" + clazz.getName() + "]类上必须有@Table注解");
   CLASS_TO_TABLE_MAPPING.put(clazz, StringUtils.hasText(table.value()) ? table.value() : doFormatWithHunmRule(clazz.getSimpleName()));
 }
 /**
  * 通过Filed建立属性名称到字段名称的映射
  *
  * @param clazz
  * @param mappings
  */
 private void buildFiledToColumnMapping(Class<?> clazz, Map<Field, String> mappings) {
   ReflectionUtils.doWithLocalFields(clazz, (field) -> {
       Column column = field.getAnnotation(Column.class);
       if (column != null) {
         if (Modifier.isStatic(field.getModifiers())) {
           LOGGER.error("[{}]注解不适用于静态方法:[{}]", Column.class.toString(), field);
           return;
         }
         mappings.put(field, StringUtils.hasText(column.value()) ? column.value() : doFormatWithHunmRule(field.getName()));
       }
     }
   );
 }
 /**
  * 通过getter()建立属性名称到字段名称的映射
  *
  * @param clazz
  * @param mappings
  */
 private void buildFiledToColumnMappingWithGetter(Class<?> clazz, Map<Field, String> mappings) {
   ReflectionUtils.doWithLocalMethods(clazz, (method) -> {
       Column column = method.getAnnotation(Column.class);
       if (column != null) {
         if (Modifier.isStatic(method.getModifiers())) {
           LOGGER.warn("[{}]注解不适用于静态方法: [{}]", Column.class.toString(), method);
           return;
         }
         if (!method.getName().startsWith("get") || method.getParameterTypes().length > 0) {
           LOGGER.warn("[{}]注解只适用于getter方法,而非: [{}]方法", Column.class.toString(), method);
           return;
         }
         String fieldName = BeanUtils.findPropertyForMethod(method).getName();
         mappings.put(ReflectionUtils.findField(clazz, fieldName),
           StringUtils.hasText(column.value()) ? column.value() : doFormatWithHunmRule(fieldName));
       }
     }
   );
 }
 /**
  * 依据驼峰原则格式化属性或者类名称,在驼峰处改小写同时前一位插入下划线,忽略首字母
  *
  * @param name
  * @return
  */
 private static String doFormatWithHunmRule(String name) {
   Assert.hasText(name, "属性或者类名称不能为空");
   SB.delete(0, SB.length());
   SB.append(toUpperCase(name.charAt(0)));
   for (int i = 1; i < name.length(); i++) {
     if (isUpperCase(name.charAt(i))) {
       SB.append("_");
     }
     SB.append(toUpperCase(name.charAt(i)));
   }
   return SB.toString();
 }
 /**
  * 将字符转换为大写
  *
  * @param ch
  * @return
  */
 private static char toUpperCase(char ch) {
   return Character.toUpperCase(ch);
 }
 /**
  * 判断是否为大写
  *
  * @param ch
  * @return
  */
 private static boolean isUpperCase(char ch) {
   return Character.isUpperCase(ch);
 }
}

package com.bob.config.mvc.mybatis;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;
import java.util.Map.Entry;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.StringUtils;
/**
* Mybatis的SQL语句供应器
*
* @author jjb
* @create 2017-09-08 14:37
*/
public class SqlProvider {
 private static final Logger LOGGER = LoggerFactory.getLogger(SqlProvider.class);
 private TableFormatter tableFormat = new HumpToUnderLineFormatter();
 /**
  * 根据Bean对象生成插入SQL语句
  *
  * @param bean
  * @return
  */
 public String insert(Object bean) {
   Class<?> beanClass = bean.getClass();
   String tableName = tableFormat.getTableName(beanClass);
   StringBuilder insertSql = new StringBuilder();
   List<String> columns = new ArrayList<String>();
   List<String> values = new ArrayList<String>();
   insertSql.append("INSERT INTO ").append(tableName).append("(");
   try {
     for (Entry<Field, String> entry : tableFormat.getFieldMappings(beanClass).entrySet()) {
       Field field = entry.getKey();
       field.setAccessible(true);
       if (field.get(bean) != null) {
         columns.add(entry.getValue());
         values.add("#{" + field.getName() + "}");
       }
     }
   } catch (Exception e) {
     new RuntimeException("get insert sql has exceptoin:" + e);
   }
   int columnSize = columns.size();
   for (int i = 0; i < columnSize; i++) {
     insertSql.append(columns.get(i));
     insertSql.append(i != columnSize - 1 ? "," : ") VALUES(");
   }
   for (int i = 0; i < columnSize; i++) {
     insertSql.append(values.get(i));
     insertSql.append(i != columnSize - 1 ? "," : ")");
   }
   return insertSql.toString();
 }
 /**
  * 根据Bean对象生成更新SQL语句
  *
  * @param bean
  * @return
  */
 public String update(Object bean) {
   Class<?> beanClass = bean.getClass();
   String tableName = tableFormat.getTableName(beanClass);
   StringBuilder updateSql = new StringBuilder();
   updateSql.append(" UPDATE ").append(tableName).append(" SET ");
   try {
     for (Entry<Field, String> entry : tableFormat.getFieldMappings(beanClass).entrySet()) {
       Field field = entry.getKey();
       field.setAccessible(true);
       if (field.get(bean) != null) {
         updateSql.append(entry.getValue()).append("=#{").append(field.getName()).append("},");
       }
     }
     updateSql.deleteCharAt(updateSql.length() - 1);
   } catch (Exception e) {
     new RuntimeException("get update sql is exceptoin:" + e);
   }
   updateSql.append(" WHERE ").append(tableFormat.getKeyColumnName(beanClass) + " =#{" + tableFormat.getKeyFiledName(beanClass) + "}");
   return updateSql.toString();
 }
 /**
  * 根据Bean对象生成删除SQL语句
  *
  * @param bean
  * @return
  */
 public String delete(Object bean) {
   Class<?> beanClass = bean.getClass();
   String tableName = tableFormat.getTableName(beanClass);
   StringBuilder deleteSql = new StringBuilder();
   deleteSql.append(" DELETE FROM ").append(tableName).append(" WHERE ");
   try {
     for (Entry<Field, String> entry : tableFormat.getFieldMappings(beanClass).entrySet()) {
       Field field = entry.getKey();
       field.setAccessible(true);
       if (field.get(bean) != null) {
         deleteSql.append(entry.getValue()).append("=#{").append(field.getName()).append("} AND ");
       }
     }
     deleteSql.delete(deleteSql.length() - 5, deleteSql.length() - 1);
   } catch (Exception e) {
     new RuntimeException("get delete sql is exceptoin:" + e);
   }
   return deleteSql.toString();
 }
 /**
  * 生成查询SQL语句
  *
  * @param bean
  * @return
  */
 public String select(Object bean) {
   Class<?> beanClass = bean.getClass();
   String tableName = tableFormat.getTableName(beanClass);
   StringBuilder selectSql = new StringBuilder();
   List<String> columns = new ArrayList<String>();
   List<String> values = new ArrayList<String>();
   selectSql.append("SELECT ");
   try {
     for (Entry<Field, String> entry : tableFormat.getFieldMappings(beanClass).entrySet()) {
       Field field = entry.getKey();
       field.setAccessible(true);
       selectSql.append(entry.getValue() + ",");
       if (field.get(bean) != null) {
         columns.add(entry.getValue());
         values.add("#{" + field.getName() + "}");
       }
     }
     selectSql.deleteCharAt(selectSql.length() - 1);
   } catch (Exception e) {
     new RuntimeException("get select sql is exceptoin:" + e);
   }
   selectSql.append(" FROM ").append(tableName).append(" WHERE ");
   int columnSize = columns.size();
   for (int i = 0; i < columnSize; i++) {
     selectSql.append(columns.get(i)).append("=").append(values.get(i)).append(" AND ");
   }
   selectSql.delete(selectSql.length() - 5, selectSql.length() - 1);
   return selectSql.toString();
 }
}

package com.bob.test.concrete.mysqlGenerate;
import java.time.LocalDate;
import com.bob.config.mvc.mybatis.MybatisEntity;
import com.bob.config.mvc.mybatis.SqlProvider;
import org.junit.Before;
import org.junit.Test;
/**
* Mysql基于注解形式的sql语句生成测试
*
* @author jjb
* @create 2017-09-11 11:10
*/
public class MysqlGenerateTest {
 private SqlProvider sqlProvider;
 private MybatisEntity mybatisEntity;
 @Before
 public void doBefore(){
   sqlProvider = new SqlProvider();
   mybatisEntity = new MybatisEntity();
   mybatisEntity.setId("0015415");
   mybatisEntity.setName("lanboal");
   mybatisEntity.setAge(28);
   mybatisEntity.setDate(LocalDate.now());
   mybatisEntity.setUserAdressNumber(24);
 }
 @Test
 public void testInsert(){
   String sql = sqlProvider.insert(mybatisEntity);
   System.out.println(sql);
 }
 @Test
 public void testUpdate(){
   String sql = sqlProvider.update(mybatisEntity);
   System.out.println(sql);
 }
 @Test
 public void testDelete(){
   String sql = sqlProvider.delete(mybatisEntity);
   System.out.println(sql);
 }
 @Test
 public void testSelect(){
   String sql = sqlProvider.select(mybatisEntity);
   System.out.println(sql);
 }
}

总结

以上所述是小编给大家介绍的 Mybatis基于注解形式的sql语句生成实例代码网站的支持！

来源：http://blog.csdn.net/longdayu4544/article/details/77931795