sql中带有like时如何使用预编译。

String str = "长江";
Connection conn = null; 
//比较preparestatement和statement 
PreparedStatement ps = null; 
ResultSet rs = null; 
try { 
//2.建立连接 
conn = JdbcUtils.getConnection(); 
//3.创建语句 
String stl = "SELECT * FROM jeesci WHERE title like ?"; 
ps = conn.prepareStatement(stl); 
//将第一个问号替换成str
ps.setString(1, "%"+str+"%");

//4.执行语句 
rs = ps.executeQuery();