Java——异常处理，数据库连接

<span style="color: #008080"> 1</span> <span style="color: #0000ff">import</span><span style="color: #000000"> java.sql.Connection;
</span><span style="color: #008080"> 2</span> <span style="color: #0000ff">import</span><span style="color: #000000"> java.sql.DriverManager;
</span><span style="color: #008080"> 3</span> <span style="color: #0000ff">import</span><span style="color: #000000"> java.sql.ResultSet;
</span><span style="color: #008080"> 4</span> <span style="color: #0000ff">import</span><span style="color: #000000"> java.sql.Statement;
</span><span style="color: #008080"> 5</span> 
<span style="color: #008080"> 6</span> <span style="color: #008000">/**</span>
<span style="color: #008080"> 7</span> <span style="color: #008000"> * Created by BoGummyYoung on 2017/4/6.
</span><span style="color: #008080"> 8</span>  <span style="color: #008000">*/</span>
<span style="color: #008080"> 9</span> <span style="color: #0000ff">public</span> <span style="color: #0000ff">class</span><span style="color: #000000"> ConnMySql
</span><span style="color: #008080">10</span> <span style="color: #000000">{
</span><span style="color: #008080">11</span>     <span style="color: #0000ff">public</span> <span style="color: #0000ff">static</span> <span style="color: #0000ff">void</span> main(String[] args) <span style="color: #0000ff">throws</span><span style="color: #000000"> Exception
</span><span style="color: #008080">12</span> <span style="color: #000000">    {
</span><span style="color: #008080">13</span>         <span style="color: #008000">//</span><span style="color: #008000">1.加载驱动，使用反射知识，现在记住这么写</span>
<span style="color: #008080">14</span>         Class.forName("com.mysql.jdbc.Driver"<span style="color: #000000">);
</span><span style="color: #008080">15</span>         <span style="color: #0000ff">try</span><span style="color: #000000">(
</span><span style="color: #008080">16</span>                 <span style="color: #008000">//</span><span style="color: #008000">2.使用DriverManager获取数据库连接
</span><span style="color: #008080">17</span>                 <span style="color: #008000">//</span><span style="color: #008000">其中返回的Connection就代表了Java程序和数据库的连接
</span><span style="color: #008080">18</span>                 <span style="color: #008000">//</span><span style="color: #008000">不同数据库的URL写法需要查驱动文档，用户名、密码由DBA分配</span>
<span style="color: #008080">19</span>                 Connection conn =<span style="color: #000000"> DriverManager.getConnection(
</span><span style="color: #008080">20</span>                         "jdbc:mysql://localhost:3306/select_test"
<span style="color: #008080">21</span>                         ,"root","bogummy"<span style="color: #000000">);
</span><span style="color: #008080">22</span>                 <span style="color: #008000">//</span><span style="color: #008000">3.使用Connection来创建一个Statement对象</span>
<span style="color: #008080">23</span>                 Statement stmt =<span style="color: #000000"> conn.createStatement();
</span><span style="color: #008080">24</span>                 <span style="color: #008000">//</span><span style="color: #008000">4.执行SQL语句</span>
<span style="color: #008080">25</span>                 <span style="color: #008000">/*</span>
<span style="color: #008080">26</span> <span style="color: #008000">                Statement 有三种执行SQL语句的方法：
</span><span style="color: #008080">27</span> <span style="color: #008000">                1.execute()可执行任何SQL语句——返回一个boolean值
</span><span style="color: #008080">28</span> <span style="color: #008000">                  如果执行后第一个结果是ResultSet，则返回true，否则返回false
</span><span style="color: #008080">29</span> <span style="color: #008000">                2.executeQuery()执行select语句——返回查询到的结果集
</span><span style="color: #008080">30</span> <span style="color: #008000">                3.executeUpdate()用于执行DML语句——返回一个整数
</span><span style="color: #008080">31</span> <span style="color: #008000">                  代表被SQL语句影响的记录条数
</span><span style="color: #008080">32</span>                  <span style="color: #008000">*/</span>
<span style="color: #008080">33</span>                 ResultSet rs = stmt.executeQuery("select s.*, teacher_name"
<span style="color: #008080">34</span>                 +" from student_table s , teacher_table t"
<span style="color: #008080">35</span>                 +" where t.teacher_id = s.java_teacher"<span style="color: #000000">))
</span><span style="color: #008080">36</span> <span style="color: #000000">        {
</span><span style="color: #008080">37</span>             <span style="color: #008000">//</span><span style="color: #008000">ResultSet有一系列的getXxx(列索引 | 列名)方法，用于获取记录指针
</span><span style="color: #008080">38</span>             <span style="color: #008000">//</span><span style="color: #008000">指向行、列特定的值，不断地使用next()将记录指针下移一行
</span><span style="color: #008080">39</span>             <span style="color: #008000">//</span><span style="color: #008000">如果移动之后记录指针依然指向有效行，则next()方法返回true</span>
<span style="color: #008080">40</span>             <span style="color: #0000ff">while</span><span style="color: #000000">(rs.next())
</span><span style="color: #008080">41</span> <span style="color: #000000">            {
</span><span style="color: #008080">42</span>                 System.out.println(rs.getInt(1) + "\t"
<span style="color: #008080">43</span>                      + rs.getString(2) + "\t"
<span style="color: #008080">44</span>                      + rs.getString(3) + "\t"
<span style="color: #008080">45</span>                      + rs.getString(4) + "\t"<span style="color: #000000">);
</span><span style="color: #008080">46</span> <span style="color: #000000">            }
</span><span style="color: #008080">47</span> <span style="color: #000000">        }
</span><span style="color: #008080">48</span> <span style="color: #000000">    }
</span><span style="color: #008080">49</span> }

基本的异常处理：

<span style="color: #008080">1</span> <span style="color: #0000ff">try</span>
<span style="color: #008080">2</span> <span style="color: #000000">{
</span><span style="color: #008080">3</span>       <span style="color: #008000">//</span><span style="color: #008000">业务实现代码</span>
<span style="color: #008080">4</span> <span style="color: #000000">      ...
</span><span style="color: #008080">5</span> <span style="color: #000000">}
</span><span style="color: #008080">6</span> <span style="color: #0000ff">catch</span> ( ) 

Java——异常处理，数据库连接

标签：exception   one   als   imp   需要   state   bool   test   异常处理