java 错误: 未报告的异常错误Exception; 必须对其进行捕获或声明以便抛出
1 import java.io.FileInputStream; 2 import java.util.Properties; 3 import java.sql.Connection; 4 import java.sql.DriverManager; 5 import java.sql.Statement; 6 7 public class ExecuteDML{ 8 private String driver; 9 private String url; 10 private String user; 11 private String pass; 12 13 public void initParam(String paramFile) throws Exception{ 14 Properties props = new Properties(); 15 props.load(new FileInputStream(paramFile)); 16 driver = props.getProperty("driver"); 17 url = props.getProperty("url"); 18 user = props.getProperty("user"); 19 pass = props.getProperty("pass"); 20 } 21 22 public int insertData(String sql) throws Exception{ 23 //加载驱动 24 Class.forName(driver); 25 try( 26 //获取数据库连接 27 Connection conn = DriverManager.getConnection(url, user, pass); 28 //使用Connection来创建一个Statement对象 29 Statement stmt = conn.createStatement()){ 30 //执行SQL语句，返回受影响的记录条数 31 return stmt.executeUpdate(sql); 32 } 33 } 34 35 public static void main(String[] args) { 36 ExecuteDML ed = new ExecuteDML(); 37 ed.initParam("mysql.ini"); 38 int result = ed.insertData("insert into jdbc_test(jdbc_name,jdbc_desc)" 39 + "select s.student_name , t.teacher_name " 40 + "from student_table s , teacher_table t " 41 + "where s.java_teacher = t.teacher_id;"); 42 System.out.println("------系统中一共有" + result + "条记录受影响------"); 43 } 44 }
出错是因为，对initParam()方法和insertData()方法抛出的异常没有进行处理，解决办法：
1.main()方法中在try...catch块中调用initParam()和insertData()方法
2.main()方法throws抛出异常。
1 import java.io.FileInputStream; 2 import java.util.Properties; 3 import java.sql.Connection; 4 import java.sql.DriverManager; 5 import java.sql.Statement; 6 7 public class ExecuteDML{ 8 private String driver; 9 private String url; 10 private String user; 11 private String pass; 12 13 public void initParam(String paramFile) throws Exception{ 14 Properties props = new Properties(); 15 props.load(new FileInputStream(paramFile)); 16 driver = props.getProperty("driver"); 17 url = props.getProperty("url"); 18 user = props.getProperty("user"); 19 pass = props.getProperty("pass"); 20 } 21 22 public int insertData(String sql) throws Exception{ 23 //加载驱动 24 Class.forName(driver); 25 try( 26 //获取数据库连接 27 Connection conn = DriverManager.getConnection(url, user, pass); 28 //使用Connection来创建一个Statement对象 29 Statement stmt = conn.createStatement()){ 30 //执行SQL语句，返回受影响的记录条数 31 return stmt.executeUpdate(sql); 32 } 33 } 34 35 public static void main(String[] args) throws Exception{ 36 ExecuteDML ed = new ExecuteDML(); 37 ed.initParam("mysql.ini"); 38 int result = ed.insertData("insert into jdbc_test(jdbc_name,jdbc_desc)" 39 + "select s.student_name , t.teacher_name " 40 + "from student_table s , teacher_table t " 41 + "where s.java_teacher = t.teacher_id;"); 42 System.out.println("------系统中一共有" + result + "条记录受影响------"); 43 } 44 }
