我使用是三个类 JDBCTools ，ReflectionUtils,JDBCTest我调用JDBCTest中的 testResultSetMetaData() 查询Student 时一直发生 java.lang.IllegalArgumentException异常用的是Oracle 数据库 下面是代码和截图 求教 实在想不出哪里出错了下面代码分别是JDBCTest ReflectionUtils JDBCTools Student 四个类 数据库建立的表create table examstudents4 (flow_id number(3),type_id number(3),id_card varchar2(20),exam_card varchar2(20),student_name varchar2(20),location varchar2(20),grade number(3))连接数据库的配置文件 文件名字 jdbc.propertiesdriver=oracle.jdbc.driver.OracleDriverjdbcUrl=jdbc:oracle:thin:@localhost:1521:orcluser=scottpassword=tigerimport static org.junit.Assert.*;//import java.util.Properties;//import java.util.Scanner;//import java.io.File;//import java.io.FileInputStream;//import java.io.IOException;//import java.io.InputStream;//import java.sql.Connection;//import java.sql.Driver;//import java.sql.DriverManager;//import java.sql.PreparedStatement;//import java.sql.ResultSet;//import java.sql.ResultSetMetaData;//import java.sql.SQLException;//import java.sql.Statement;//import org.junit.Test;//import java.util.*;//import java.util.Map;;import java.sql.Connection;import java.sql.Date;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.ResultSetMetaData;import java.sql.Statement;import java.util.HashMap;import java.util.Map;import java.util.Scanner;import org.junit.Test;public class JDBCTest1 {@Testpublic void testGet() {String sql = "SELECT id, name, email, birth "+ "FROM customers WHERE id = ?";// System.out.println(sql);//// Customer customer = get(Customer.class, sql, 5);// System.out.println(customer);sql = "SELECT flow_id flowId, type_id type, id_card idCard, "+ "exam_card examCard, student_name studentName, "+ "location, grade " + "FROM examstudent3 WHERE flow_id = ?";// System.out.println(sql);Student stu = get(Student.class, sql, 1);System.out.println(stu);}/*** 通用的查询方法：可以根据传入的 SQL、Class 对象返回 SQL 对应的记录的对象* @param clazz: 描述对象的类型* @param sql: SQL 语句。可能带占位符* @param args: 填充占位符的可变参数。* @return*/public <T> T get(Class<T> clazz, String sql, Object... args) {T entity = null;Connection connection = null;PreparedStatement preparedStatement = null;ResultSet resultSet = null;try {//1. 得到 ResultSet 对象connection = JDBCTools.getConnection();preparedStatement = connection.prepareStatement(sql);for (int i = 0; i < args.length; i++) {preparedStatement.setObject(i + 1, args[i]);}resultSet = preparedStatement.executeQuery();//2. 得到 ResultSetMetaData 对象ResultSetMetaData rsmd = resultSet.getMetaData();//3. 创建一个 Map<String, Object> 对象, 键: SQL 查询的列的别名, //值: 列的值Map<String, Object> values = new HashMap<String,Object>();//4. 处理结果集. 利用 ResultSetMetaData 填充 3 对应的 Map 对象if(resultSet.next()){for(int i = 0; i < rsmd.getColumnCount(); i++){String columnLabel = rsmd.getColumnLabel(i + 1);Object columnValue = resultSet.getObject(i + 1);values.put(columnLabel, columnValue);}}//5. 若 Map 不为空集, 利用反射创建 clazz 对应的对象if(values.size() > 0){entity = clazz.newInstance();//5. 遍历 Map 对象, 利用反射为 Class 对象的对应的属性赋值. for(Map.Entry<String, Object> entry: values.entrySet()){String fieldName = entry.getKey();Object value = entry.getValue();ReflectionUtils.setFieldValue(entity, fieldName, value);}}} catch (Exception e) {e.printStackTrace();} finally {JDBCTools.releaseDB(resultSet, preparedStatement, connection);}return entity;}@Testpublic void testResultSetMetaData1() {Connection connection = null;PreparedStatement preparedStatement = null;ResultSet resultSet = null;try {String sql = "SELECT flow_id flowId, type_id type, id_card idCard, "+ "exam_card examCard, student_name studentName, "+ "location location, grade grade " + "FROM examstudent3 WHERE flow_id = ?";connection = JDBCTools.getConnection();preparedStatement = connection.prepareStatement(sql);preparedStatement.setInt(1, 1);resultSet = preparedStatement.executeQuery();Map<String, Object> values = new HashMap<String, Object>();//1. 得到 ResultSetMetaData 对象ResultSetMetaData rsmd = resultSet.getMetaData();while(resultSet.next()){//2. 打印每一列的列名for(int i = 0; i < rsmd.getColumnCount(); i++){String columnLabel = rsmd.getColumnLabel(i + 1);Object columnValue = resultSet.getObject(columnLabel);values.put(columnLabel, columnValue);}}//System.out.println(values); Class clazz = Student.class;Object object = clazz.newInstance();for(Map.Entry<String, Object> entry: values.entrySet()){String fieldName = entry.getKey();Object fieldValue = entry.getValue();// System.out.println(fieldName + ": " + fieldValue);ReflectionUtils.setFieldValue(object, fieldName, fieldValue);}System.out.println(object); } catch (Exception e) {e.printStackTrace();} finally {JDBCTools.releaseDB(resultSet, preparedStatement, connection);}}}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;}}import java.io.IOException;import java.io.InputStream;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import java.util.Properties;public class JDBCTools {/*** 执行 SQL 语句, 使用 PreparedStatement* @param sql* @param args: 填写 SQL 占位符的可变参数*/public static void update(String sql, Object ... args){Connection connection = null;PreparedStatement preparedStatement = null;try {connection = JDBCTools.getConnection();preparedStatement = connection.prepareStatement(sql);for(int i = 0; i < args.length; i++){preparedStatement.setObject(i + 1, args[i]);}preparedStatement.executeUpdate();} catch (Exception e) {e.printStackTrace();} finally{JDBCTools.releaseDB(null, preparedStatement, connection);}}/*** 执行 SQL 的方法* * @param sql: insert, update 或 delete。 而不包含 select*/public static void update(String sql) {Connection connection = null;Statement statement = null;try {// 1. 获取数据库连接connection = getConnection();// 2. 调用 Connection 对象的 createStatement() 方法获取 Statement 对象statement = connection.createStatement();// 4. 发送 SQL 语句: 调用 Statement 对象的 executeUpdate(sql) 方法statement.executeUpdate(sql);} catch (Exception e) {e.printStackTrace();} finally {// 5. 关闭数据库资源: 由里向外关闭.releaseDB(null, statement, connection);}}/*** 释放数据库资源的方法* * @param resultSet* @param statement* @param connection*/public static void releaseDB(ResultSet resultSet, Statement statement,Connection connection) {if (resultSet != null) {try {resultSet.close();} catch (SQLException e) {e.printStackTrace();}}if (statement != null) {try {statement.close();} catch (SQLException e) {e.printStackTrace();}}if (connection != null) {try {connection.close();} catch (SQLException e) {e.printStackTrace();}}}/*** 获取数据库连接的方法*/public static Connection getConnection() throws IOException,ClassNotFoundException, SQLException {// 0. 读取 jdbc.properties/*** 1). 属性文件对应 Java 中的 Properties 类 2). 可以使用类加载器加载 bin 目录(类路径下)的文件*/Properties properties = new Properties();InputStream inStream = JDBCTools.class.getClassLoader().getResourceAsStream("jdbc.properties");properties.load(inStream);// 1. 准备获取连接的 4 个字符串: user, password, jdbcUrl, driverClassString user = properties.getProperty("user");String password = properties.getProperty("password");String jdbcUrl = properties.getProperty("jdbcUrl");String driverClass = properties.getProperty("driver");// 2. 加载驱动: Class.forName(driverClass)Class.forName(driverClass);// 3. 调用// DriverManager.getConnection(jdbcUrl, user, password)// 获取数据库连接Connection connection = DriverManager.getConnection(jdbcUrl, user,password);return connection;}}public class Student {// 流水号private int flowId;// 考试的类型private int type;// 身份证号private String idCard;// 准考证号private String examCard;// 学生名private String studentName;// 学生地址private String location;// 考试分数.private int grade;public int getFlowId() {return flowId;}public void setFlowId(int flowId) {this.flowId = flowId;}public int getType() {return type;}public void setType(int type) {this.type = type;}public String getIdCard() {return idCard;}public void setIdCard(String idCard) {this.idCard = idCard;}public String getExamCard() {return examCard;}public void setExamCard(String examCard) {this.examCard = examCard;}public String getStudentName() {return studentName;}public void setStudentName(String studentName) {this.studentName = studentName;}public String getLocation() {return location;}public void setLocation(String location) {this.location = location;}public int getGrade() {return grade;}public void setGrade(int grade) {this.grade = grade;}public Student(int flowId, int type, String idCard, String examCard,String studentName, String location, int grade) {super();this.flowId = flowId;this.type = type;this.idCard = idCard;this.examCard = examCard;this.studentName = studentName;this.location = location;this.grade = grade;}public Student() {// TODO Auto-generated constructor stub}@Overridepublic String toString() {return "Student [flowId=" + flowId + ", type=" + type + ", idCard="+ idCard + ", examCard=" + examCard + ", studentName="+ studentName + ", location=" + location + ", grade=" + grade+ "]";}}
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