jdbcTemplate的Dao层封装

 package com.easyrail.base.dao;

 import java.io.Serializable;
 import java.lang.reflect.Field;
 import java.lang.reflect.ParameterizedType;
 import java.sql.Types;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;

 import org.springframework.jdbc.core.BeanPropertyRowMapper;
 import org.springframework.jdbc.core.JdbcTemplate;
 import org.springframework.jdbc.core.RowMapper;

 public abstract class BaseDaoImpl<T>{
     /** 设置一些操作的常量 */
     public static final String SQL_INSERT = "insert";
     public static final String SQL_UPDATE = "update";
     public static final String SQL_DELETE = "delete";

     private JdbcTemplate jdbcTemplate;

     public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
         this.jdbcTemplate = jdbcTemplate;
     }

     private Class<T> entityClass;

     @SuppressWarnings("unchecked")
     public BaseDaoImpl() {
         ParameterizedType type = (ParameterizedType) getClass().getGenericSuperclass();
         entityClass = (Class<T>) type.getActualTypeArguments()[0];
         System.out.println("Dao实现类是：" + entityClass.getName());
     }

     public void save(T entity) {
         String sql = this.makeSql(SQL_INSERT);
         Object[] args = this.setArgs(entity, SQL_INSERT);
         int[] argTypes = this.setArgTypes(entity, SQL_INSERT);
         jdbcTemplate.update(sql.toString(), args, argTypes);
     }

     public void update(T entity) {
         String sql = this.makeSql(SQL_UPDATE);
         Object[] args = this.setArgs(entity, SQL_UPDATE);
         int[] argTypes = this.setArgTypes(entity, SQL_UPDATE);
         jdbcTemplate.update(sql, args, argTypes);
     }

     public void delete(T entity) {
         String sql = this.makeSql(SQL_DELETE);
         Object[] args = this.setArgs(entity, SQL_DELETE);
         int[] argTypes = this.setArgTypes(entity, SQL_DELETE);
         jdbcTemplate.update(sql, args, argTypes);
     }

     public void delete(Serializable id) {
         String sql = " DELETE FROM " + entityClass.getSimpleName() + " WHERE id=?";
         jdbcTemplate.update(sql, id);
     }

     public void deleteAll() {
         String sql = " TRUNCATE TABLE " + entityClass.getSimpleName();
         jdbcTemplate.execute(sql);
     }

     public T findById(Serializable id) {
         String sql = "SELECT * FROM " + entityClass.getSimpleName() + " WHERE id=?";
         RowMapper<T> rowMapper = BeanPropertyRowMapper.newInstance(entityClass);
         return jdbcTemplate.query(sql, rowMapper, id).get(0);
     }

     public List<T> findAll() {
         String sql = "SELECT * FROM " + entityClass.getSimpleName();
         RowMapper<T> rowMapper = BeanPropertyRowMapper.newInstance(entityClass);
         return jdbcTemplate.query(sql, rowMapper);
     }

     // 组装SQL
     private String makeSql(String sqlFlag) {
         StringBuffer sql = new StringBuffer();
         Field[] fields = entityClass.getDeclaredFields();
         if (sqlFlag.equals(SQL_INSERT)) {
             sql.append(" INSERT INTO " + entityClass.getSimpleName());
             sql.append("(");
             for (int i = 0; fields != null && i < fields.length; i++) {
                 fields[i].setAccessible(true); // 暴力反射
                 String column = fields[i].getName();
                 sql.append(column).append(",");
             }
             sql = sql.deleteCharAt(sql.length() - 1);
             sql.append(") VALUES (");
             for (int i = 0; fields != null && i < fields.length; i++) {
                 sql.append("?,");
             }
             sql = sql.deleteCharAt(sql.length() - 1);
             sql.append(")");
         } else if (sqlFlag.equals(SQL_UPDATE)) {
             sql.append(" UPDATE " + entityClass.getSimpleName() + " SET ");
             for (int i = 0; fields != null && i < fields.length; i++) {
                 fields[i].setAccessible(true); // 暴力反射
                 String column = fields[i].getName();
                 if (column.equals("id")) { // id 代表主键
                     continue;
                 }
                 sql.append(column).append("=").append("?,");
             }
             sql = sql.deleteCharAt(sql.length() - 1);
             sql.append(" WHERE id=?");
         } else if (sqlFlag.equals(SQL_DELETE)) {
             sql.append(" DELETE FROM " + entityClass.getSimpleName() + " WHERE id=?");
         }
         System.out.println("SQL=" + sql);
         return sql.toString();

     }

     // 设置参数
     private Object[] setArgs(T entity, String sqlFlag) {
         Field[] fields = entityClass.getDeclaredFields();
         if (sqlFlag.equals(SQL_INSERT)) {
             Object[] args = new Object[fields.length];
             for (int i = 0; args != null && i < args.length; i++) {
                 try {
                     fields[i].setAccessible(true); // 暴力反射
                     args[i] = fields[i].get(entity);
                 } catch (Exception e) {
                     e.printStackTrace();
                 }
             }
             return args;
         } else if (sqlFlag.equals(SQL_UPDATE)) {
             Object[] tempArr = new Object[fields.length];
             for (int i = 0; tempArr != null && i < tempArr.length; i++) {
                 try {
                     fields[i].setAccessible(true); // 暴力反射
                     tempArr[i] = fields[i].get(entity);
                 } catch (Exception e) {
                     e.printStackTrace();
                 }
             }
             Object[] args = new Object[fields.length];
             System.arraycopy(tempArr, 1, args, 0, tempArr.length - 1); // 数组拷贝
             args[args.length - 1] = tempArr[0];
             return args;
         } else if (sqlFlag.equals(SQL_DELETE)) {
             Object[] args = new Object[1]; // 长度是1
             fields[0].setAccessible(true); // 暴力反射
             try {
                 args[0] = fields[0].get(entity);
             } catch (Exception e) {
                 e.printStackTrace();
             }
             return args;
         }
         return null;

     }

     // 设置参数类型（写的不全，只是一些常用的）
     private int[] setArgTypes(T entity, String sqlFlag) {
         Field[] fields = entityClass.getDeclaredFields();
         if (sqlFlag.equals(SQL_INSERT)) {
             int[] argTypes = new int[fields.length];
             try {
                 for (int i = 0; argTypes != null && i < argTypes.length; i++) {
                     fields[i].setAccessible(true); // 暴力反射
                     if (fields[i].get(entity).getClass().getName().equals("java.lang.String")) {
                         argTypes[i] = Types.VARCHAR;
                     } else if (fields[i].get(entity).getClass().getName().equals("java.lang.Double")) {
                         argTypes[i] = Types.DECIMAL;
                     } else if (fields[i].get(entity).getClass().getName().equals("java.lang.Integer")) {
                         argTypes[i] = Types.INTEGER;
                     } else if (fields[i].get(entity).getClass().getName().equals("java.util.Date")) {
                         argTypes[i] = Types.DATE;
                     }
                 }
             } catch (Exception e) {
                 e.printStackTrace();
             }
             return argTypes;
         } else if (sqlFlag.equals(SQL_UPDATE)) {
             int[] tempArgTypes = new int[fields.length];
             int[] argTypes = new int[fields.length];
             try {
                 for (int i = 0; tempArgTypes != null && i < tempArgTypes.length; i++) {
                     fields[i].setAccessible(true); // 暴力反射
                     if (fields[i].get(entity).getClass().getName().equals("java.lang.String")) {
                         tempArgTypes[i] = Types.VARCHAR;
                     } else if (fields[i].get(entity).getClass().getName().equals("java.lang.Double")) {
                         tempArgTypes[i] = Types.DECIMAL;
                     } else if (fields[i].get(entity).getClass().getName().equals("java.lang.Integer")) {
                         tempArgTypes[i] = Types.INTEGER;
                     } else if (fields[i].get(entity).getClass().getName().equals("java.util.Date")) {
                         tempArgTypes[i] = Types.DATE;
                     }
                 }
                 System.arraycopy(tempArgTypes, 1, argTypes, 0, tempArgTypes.length - 1); // 数组拷贝
                 argTypes[argTypes.length - 1] = tempArgTypes[0];

             } catch (Exception e) {
                 e.printStackTrace();
             }
             return argTypes;

         } else if (sqlFlag.equals(SQL_DELETE)) {
             int[] argTypes = new int[1]; // 长度是1
             try {
                 fields[0].setAccessible(true); // 暴力反射
                 if (fields[0].get(entity).getClass().getName().equals("java.lang.String")) {
                     argTypes[0] = Types.VARCHAR;
                 } else if (fields[0].get(entity).getClass().getName().equals("java.lang.Integer")) {
                     argTypes[0] = Types.INTEGER;
                 }

             } catch (Exception e) {
                 e.printStackTrace();
             }
             return argTypes;
         }
         return null;
     }

     private List<T> find(int pageNo, int pageSize, Map<String, String> where, LinkedHashMap<String, String> orderby) {
         // where 与 order by 要写在select * from table 的后面，而不是where rownum<=? )
         // where rn>=?的后面
         StringBuffer sql = new StringBuffer(
                 " SELECT * FROM (SELECT t.*,ROWNUM rn FROM (SELECT * FROM " + entityClass.getSimpleName());
         if (where != null && where.size() > 0) {
             sql.append(" WHERE "); // 注意不是where
             for (Map.Entry<String, String> me : where.entrySet()) {
                 String columnName = me.getKey();
                 String columnValue = me.getValue();
                 sql.append(columnName).append(" ").append(columnValue).append(" AND "); // 没有考虑or的情况
             }
             int endIndex = sql.lastIndexOf("AND");
             if (endIndex > 0) {
                 sql = new StringBuffer(sql.substring(0, endIndex));
             }
         }
         if (orderby != null && orderby.size() > 0) {
             sql.append(" ORDER BY ");
             for (Map.Entry<String, String> me : orderby.entrySet()) {
                 String columnName = me.getKey();
                 String columnValue = me.getValue();
                 sql.append(columnName).append(" ").append(columnValue).append(",");
             }
             sql = sql.deleteCharAt(sql.length() - 1);
         }
         sql.append(" ) t WHERE ROWNUM<=? ) WHERE rn>=? ");
         System.out.println("SQL=" + sql);
         Object[] args = { pageNo * pageSize, (pageNo - 1) * pageSize + 1 };
         RowMapper<T> rowMapper = BeanPropertyRowMapper.newInstance(entityClass);
         return jdbcTemplate.query(sql.toString(), args, rowMapper);
     }

     private int count(Map<String, String> where) {
         StringBuffer sql = new StringBuffer(" SELECT COUNT(*) FROM " + entityClass.getSimpleName());
         if (where != null && where.size() > 0) {
             sql.append(" WHERE ");
             for (Map.Entry<String, String> me : where.entrySet()) {
                 String columnName = me.getKey();
                 String columnValue = me.getValue();
                 sql.append(columnName).append(" ").append(columnValue).append(" AND "); // 没有考虑or的情况
             }
             int endIndex = sql.lastIndexOf("AND");
             if (endIndex > 0) {
                 sql = new StringBuffer(sql.substring(0, endIndex));
             }
         }
         System.out.println("SQL=" + sql);
         return jdbcTemplate.queryForInt(sql.toString());
     }
 }