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java攻城狮之路--复习JDBC(利用BeanUtils、以及JDBC元数据编写通用的查询方法)
1、利用BeanUtils的前提得要加入以下两个jar包：
commons-beanutils-1.8.0.jar
commons-logging-1.1.1.jar
package com.shellway.jdbcDAO;import java.util.List;import org.junit.Test;public class TestDAO { DAO dao = new DAO(); @Test public void testUpdate() throws Exception { String sql = "update examstudent set grade=? where flow_id=12345"; dao.update(sql, 88); } @Test public void test() throws Exception { String sql = "select flow_id flowID,type,id_card idCard, " + "exam_card examCard,student_name studentName,location,grade " + "from examstudent where flow_id = ? "; Student stu = dao.get(Student.class, sql, 12345); System.out.println(stu); } @Test public void testGetSome() throws Exception { String sql = "select flow_id flowID,type,id_card idCard, " + "exam_card examCard,student_name studentName,location,grade " + "from examstudent"; List<Student> students = dao.getForList(Student.class, sql); System.out.println(students); } @Test public void testGetForValue() throws Exception { String sql = "select grade from examstudent where flow_id = ? "; Object obj = dao.getforvalue(sql, 123456); System.out.println(obj); }}
package com.shellway.jdbcDAO;import java.sql.Connection;import java.sql.ResultSet;import java.sql.PreparedStatement;import java.sql.ResultSetMetaData;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import org.apache.commons.beanutils.BeanUtils;public class DAO { public void update(String sql, Object... args) throws Exception { Connection conn = null; PreparedStatement ps = null; try { conn = JDBCTools.getConnection(); ps = conn.prepareStatement(sql); for (int i = 0; i < args.length; i++) { ps.setObject(i + 1, args[i]); } ps.executeUpdate(); } catch (Exception e) { e.printStackTrace(); } finally { JDBCTools.release(null, ps, conn); } } // 获取一个对象通用的方法 public <T> T get(Class<T> clazz, String sql, Object... args) throws Exception { T entity = null; Connection conn = null; PreparedStatement ps = null; ResultSet rs = null; try { conn = JDBCTools.getConnection(); ps = conn.prepareStatement(sql); for (int i = 0; i < args.length; i++) { ps.setObject(i + 1, args[i]); } rs = ps.executeQuery(); ResultSetMetaData rsmd = rs.getMetaData(); Map<String, Object> map = null; while (rs.next()) { map = new HashMap<String, Object>(); for (int i = 0; i < rsmd.getColumnCount(); i++) { String columnLabel = rsmd.getColumnLabel(i + 1); Object columnValue = rs.getObject(i + 1); map.put(columnLabel, columnValue); } if (map.size() > 0) { entity = clazz.newInstance(); for (Map.Entry<String, Object> entry : map.entrySet()) { String label = entry.getKey(); Object value = entry.getValue(); BeanUtils.setProperty(entity, label, value); } } } } catch (Exception e) { e.printStackTrace(); } finally { JDBCTools.release(rs, ps, conn); } return entity; } // 获取一组对象通用的方法 public <T> List<T> getForList(Class<T> clazz, String sql, Object... args) throws Exception { T entity = null; Connection conn = null; PreparedStatement ps = null; ResultSet rs = null; List<T> result = new ArrayList<T>(); try { conn = JDBCTools.getConnection(); ps = conn.prepareStatement(sql); for (int i = 0; i < args.length; i++) { ps.setObject(i + 1, args[i]); } rs = ps.executeQuery(); ResultSetMetaData rsmd = rs.getMetaData(); List<Map<String, Object>> list = new ArrayList<Map<String, Object>>(); Map<String, Object> map = new HashMap<String, Object>(); while (rs.next()) { for (int i = 0; i < rsmd.getColumnCount(); i++) { String columnLabel = rsmd.getColumnLabel(i + 1); Object columnValue = rs.getObject(i + 1); map.put(columnLabel, columnValue); } list.add(map); if (list.size() > 0) { entity = clazz.newInstance(); for (Map<String, Object> ll : list) { for (Map.Entry<String, Object> entry : ll.entrySet()) { String label = entry.getKey(); Object value = entry.getValue(); BeanUtils.setProperty(entity, label, value); } } result.add(entity); } } } catch (Exception e) { e.printStackTrace(); } finally { JDBCTools.release(rs, ps, conn); } return result; } // 获取一个对象中一列的值通用的方法 public <E> E getforvalue(String sql, Object... args) throws Exception { Connection conn = null; PreparedStatement ps = null; ResultSet rs = null; try { conn = JDBCTools.getConnection(); ps = conn.prepareStatement(sql); for (int i = 0; i < args.length; i++) { ps.setObject(i + 1, args[i]); } rs = ps.executeQuery(); if (rs.next()) { return (E) rs.getObject(1); } } catch (Exception e) { e.printStackTrace(); } finally { JDBCTools.release(rs, ps, conn); } return null; }}
package com.shellway.jdbcDAO;import java.io.InputStream;import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.ResultSetMetaData;import java.sql.Statement;import java.util.HashMap;import java.util.Map;import java.util.Properties;import java.sql.PreparedStatement;public class JDBCTools { public static <T> T get(Class<T> clazz, String sql, Object... args) throws Exception { T entity = null; Connection conn = null; PreparedStatement ps = null; ResultSet rs = null; try { conn = JDBCTools.getConnection(); ps = conn.prepareStatement(sql); for (int i = 0; i < args.length; i++) { ps.setObject(i + 1, args[i]); } rs = ps.executeQuery(); ResultSetMetaData rsmd = rs.getMetaData(); Map<String, Object> map = new HashMap<String, Object>(); while (rs.next()) { for (int i = 0; i < rsmd.getColumnCount(); i++) { String columnLabel = rsmd.getColumnLabel(i + 1); Object columnValue = rs.getObject(i + 1); // Object columnValue = http://www.mamicode.com/rs.getObject(columnLabel); map.put(columnLabel, columnValue); } } if (map.size() > 0) { entity = clazz.newInstance(); for (Map.Entry<String, Object> values : map.entrySet()) { String key = values.getKey(); Object value = values.getValue(); ReflectionUtils.setFieldValue(entity, key, value); } } } catch (Exception e) { e.printStackTrace(); } finally { JDBCTools.release(rs, ps, conn); } return entity; } public static void update(String sql, Object... args) throws Exception { Connection conn = null; PreparedStatement ps = null; try { conn = JDBCTools.getConnection(); ps = conn.prepareStatement(sql); for (int i = 0; i < args.length; i++) { ps.setObject(i + 1, args[i]); } System.out.println(sql); ps.executeUpdate(); } catch (Exception e) { e.printStackTrace(); } finally { JDBCTools.release(null, ps, conn); } } public static Connection getConnection() throws Exception { Properties proper = new Properties(); InputStream in = JDBCTools.class.getClassLoader().getResourceAsStream( "jdbc.properties"); proper.load(in); String driverClass = proper.getProperty("driver"); String jdbcUrl = proper.getProperty("jdbcUrl"); String user = proper.getProperty("user"); String password = proper.getProperty("password"); Class.forName(driverClass); Connection connection = DriverManager.getConnection(jdbcUrl, user, password); return connection; } public static void release(ResultSet rs, Statement state, Connection conn) throws Exception { if (rs != null) { try { rs.close(); } catch (Exception e) { e.printStackTrace(); } } if (state != null) { try { state.close(); } catch (Exception e) { e.printStackTrace(); } } if (conn != null) { try { conn.close(); } catch (Exception e) { e.printStackTrace(); } } }}
driver=com.mysql.jdbc.DriverjdbcUrl=jdbc:mysql://localhost:3306/testuser=rootpassword=123
package com.shellway.jdbc;import java.lang.reflect.Field;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.lang.reflect.Modifier;import java.lang.reflect.ParameterizedType;import java.lang.reflect.Type;/** * 反射的 Utils 函数集合 提供访问私有变量, 获取泛型类型 Class, 提取集合中元素属性等 Utils 函数 * * @author Administrator * */public class ReflectionUtils { /** * 通过反射, 获得定义 Class 时声明的父类的泛型参数的类型 如: public EmployeeDao extends * BaseDao<Employee, String> * * @param clazz * @param index * @return */ @SuppressWarnings("unchecked") public static Class getSuperClassGenricType(Class clazz, int index) { Type genType = clazz.getGenericSuperclass(); if (!(genType instanceof ParameterizedType)) { return Object.class; } Type[] params = ((ParameterizedType) genType).getActualTypeArguments(); if (index >= params.length || index < 0) { return Object.class; } if (!(params[index] instanceof Class)) { return Object.class; } return (Class) params[index]; } /** * 通过反射, 获得 Class 定义中声明的父类的泛型参数类型 如: public EmployeeDao extends * BaseDao<Employee, String> * * @param <T> * @param clazz * @return */ @SuppressWarnings("unchecked") public static <T> Class<T> getSuperGenericType(Class clazz) { return getSuperClassGenricType(clazz, 0); } /** * 循环向上转型, 获取对象的 DeclaredMethod * * @param object * @param methodName * @param parameterTypes * @return */ public static Method getDeclaredMethod(Object object, String methodName, Class<?>[] parameterTypes) { for (Class<?> superClass = object.getClass(); superClass != Object.class; superClass = superClass .getSuperclass()) { try { // superClass.getMethod(methodName, parameterTypes); return superClass.getDeclaredMethod(methodName, parameterTypes); } catch (NoSuchMethodException e) { // Method 不在当前类定义, 继续向上转型 } // .. } return null; } /** * 使 filed 变为可访问 * * @param field */ public static void makeAccessible(Field field) { if (!Modifier.isPublic(field.getModifiers())) { field.setAccessible(true); } } /** * 循环向上转型, 获取对象的 DeclaredField * * @param object * @param filedName * @return */ public static Field getDeclaredField(Object object, String filedName) { for (Class<?> superClass = object.getClass(); superClass != Object.class; superClass = superClass .getSuperclass()) { try { return superClass.getDeclaredField(filedName); } catch (NoSuchFieldException e) { // Field 不在当前类定义, 继续向上转型 } } return null; } /** * 直接调用对象方法, 而忽略修饰符(private, protected) * * @param object * @param methodName * @param parameterTypes * @param parameters * @return * @throws InvocationTargetException * @throws IllegalArgumentException */ public static Object invokeMethod(Object object, String methodName, Class<?>[] parameterTypes, Object[] parameters) throws InvocationTargetException { Method method = getDeclaredMethod(object, methodName, parameterTypes); if (method == null) { throw new IllegalArgumentException("Could not find method [" + methodName + "] on target [" + object + "]"); } method.setAccessible(true); try { return method.invoke(object, parameters); } catch (IllegalAccessException e) { System.out.println("不可能抛出的异常"); } return null; } /** * 直接设置对象属性值, 忽略 private/protected 修饰符, 也不经过 setter * * @param object * @param fieldName * @param value */ public static void setFieldValue(Object object, String fieldName, Object value) { Field field = getDeclaredField(object, fieldName); if (field == null) throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + object + "]"); makeAccessible(field); try { field.set(object, value); } catch (IllegalAccessException e) { System.out.println("不可能抛出的异常"); } } /** * 直接读取对象的属性值, 忽略 private/protected 修饰符, 也不经过 getter * * @param object * @param fieldName * @return */ public static Object getFieldValue(Object object, String fieldName) { Field field = getDeclaredField(object, fieldName); if (field == null) throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + object + "]"); makeAccessible(field); Object result = null; try { result = field.get(object); } catch (IllegalAccessException e) { System.out.println("不可能抛出的异常"); } return result; }}
2、获取数据库中的一些元数据：
@Test public void testDatebaseMetaData() throws Exception { Connection conn = null; ResultSet rs = null; try { conn = JDBCTools.getConnection(); DatabaseMetaData dbmd = conn.getMetaData(); // 得到数据库的一些基本信息 int version = dbmd.getDatabaseMajorVersion(); System.out.println(version); String user = dbmd.getUserName(); System.out.println(user); rs = dbmd.getCatalogs(); while (rs.next()) { String str = rs.getString(1); System.out.println(str); } } catch (Exception e) { e.printStackTrace(); } finally { JDBCTools.release(rs, null, conn); } }
3、获取插入记录的主键值，在加入购物车时用到
@Test public void testPrimeryKey() throws Exception { Connection conn = null; PreparedStatement ps = null; ResultSet rs = null; String sql = "insert into customer(name,email,birth) values(?,?,?) "; try { conn = JDBCTools.getConnection(); ps = conn.prepareStatement(sql, ps.RETURN_GENERATED_KEYS); ps.setString(1, "BBBB"); ps.setString(2, "BBBB@163.COM"); ps.setDate(3, new Date(new java.util.Date().getTime())); ps.executeUpdate(); rs = ps.getGeneratedKeys(); if (rs.next()) { Object obj = rs.getObject(1); System.out.println(obj); } } catch (Exception e) { e.printStackTrace(); } finally { JDBCTools.release(null, ps, conn); } }
java攻城狮之路--复习JDBC(利用BeanUtils、以及JDBC元数据编写通用的查询方法)
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