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服务器之家 - 编程语言 - Java教程 - Mybatis基于注解形式的sql语句生成实例代码

Mybatis基于注解形式的sql语句生成实例代码

2021-01-01 12:13jjb_hz Java教程

这篇文章主要介绍了 Mybatis基于注解形式的sql语句生成实例代码,需要的朋友可以参考下

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。

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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;
}
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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();
}
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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);
}
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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;
  }
}
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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);
}
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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);
  }
}
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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();
  }
}
?
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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，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对服务器之家网站的支持！

原文链接：http://blog.csdn.net/longdayu4544/article/details/77931795

  • 注解
  • mybatis
  • SQL

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