使用JDBC进行简单的增删改查
JDBC为java的基础。用jdbc实现对数据库的增删改查的功能是程序员的基本要求。本例以mysql为例,首先要使用本例需要添加mysql-connector-java-5.1.7-bin.jar包。专门用来加载jdbc的驱动。如果数据库为oracle,相应的jar包换为ojdbc6.jar。
通过下面的代码可以练习一下,掌握jdbc的使用方法,自己可以对程序进行相应的扩展,可以试试oracle数据库,也可以试试MongoDB,还可以试试redis等。
package jdbc; import java.sql.*; import java.util.UUID; public class JDBC_Test { public static Connection getConnection() throws Exception { String driver_mysql = "com.mysql.jdbc.Driver"; Class.forName(driver_mysql); // 数据库连接串 String mysql_url ="jdbc:mysql://127.0.0.1:3306/jdbc"; String userName = "root"; String password = "xiangpeng";//密码 // 获取数据库连接 Connection conn = DriverManager.getConnection(mysql_url, userName, password); return conn; } public static void main(String[] args) throws Exception { //调用下面的方法 // JDBC_Test.createTableTest(); //建表 // JDBC_Test.addTest(); //添加 //JDBC_Test.addTest1(); // 预编译添加 // JDBC_Test.batchAddTest(); //批量添加 JDBC_Test.queryTest(); // 查询 // JDBC_Test.updateTest(); //更新 // JDBC_Test.delTest(); //删除 } //建表 public static void createTableTest()throws Exception{ Connection conn=getConnection(); String sql="create table JDBC_STUDENT3("+"ID VARCHAR2(32) NOT NULL,"+"NAME VARCHAR2(32),"+"SEX VARCHAR2(32)"+")"; PreparedStatement prestmt = conn.prepareStatement(sql); boolean flag = prestmt.execute(); System.out.println("执行结果:"+flag); prestmt.close(); conn.close(); } //添加 public static void addTest() throws Exception{ Connection conn=getConnection(); Statement stmt=conn.createStatement(); String sql="insert into jdbc_student(id, name, sex, birthday, age)"+"values(seq.nextval,'xp','m','to_date('2009-01-01','yyyy-MM-dd')','24')"; String uuid=getUUID(); String sql_uuid="insert into jdbc_student(id, name, sex, birthday, age)"+"values('"+uuid+"','xp','m','to_date('2009-01-01','yyyy-MM-dd')','24')"; int result=stmt.executeUpdate(sql_uuid); System.out.println(result); stmt.close(); conn.close(); } // java注入,采用预编译的方法插入数据 public static void addTest1() throws Exception { Connection conn = getConnection(); conn.setAutoCommit(false); String sql = "insert into jdbc_student(id, name, sex, birthday, age)"+ "values(?,?,?,?,?)"; PreparedStatement prestmt = conn.prepareStatement(sql); String uuid = getUUID(); prestmt.setString(1, uuid); prestmt.setString(2, "xp"); prestmt.setString(3, "m"); java.util.Date utilDate = new java.util.Date(); java.sql.Timestamp time = new java.sql.Timestamp(utilDate.getTime()); prestmt.setTimestamp(4, time); prestmt.setInt(5, 24); // 如果第一个结果是resultSet对象,就返回true;如果第一个结果是更新计数或者没有结果,则返回false // 意思就是如果是查询的话就返回true,如果是更新或者插入的话就返回false boolean result = prestmt.execute(); System.out.println("是否执行成功:" + result); prestmt.close(); conn.close(); } //批量添加 public static void batchAddTest()throws Exception{ Connection conn=getConnection(); //开辟缓存 conn.setAutoCommit(false); String sqla="insert into jdbc_student(id, name)"+"values('"+getUUID()+"', '张三a')"; String sqlb="insert into jdbc_student(id, name)"+"values('"+getUUID()+"', '张三b')"; String sqlc="insert into jdbc_student(id, name)"+"values('"+getUUID()+"', '张三c')"; Statement stmt =conn.createStatement(); stmt.addBatch(sqla); stmt.addBatch(sqlb); stmt.addBatch(sqlc); } //查询 public static void queryTest() throws Exception { Connection conn = getConnection(); String sql = "select * from jdbc_student t where name like ?"; PreparedStatement prestmt = conn.prepareStatement(sql); prestmt.setString(1, "王%"); ResultSet rs = prestmt.executeQuery(); ResultSetMetaData rsmd = rs.getMetaData();// 获取元数据 int columnNum = rsmd.getColumnCount(); while (rs.next()) { for (int i = 1; i <= columnNum; i++) { System.out.print(rsmd.getColumnName(i) + ": "); System.out.println(JDBC_Test.getValue(rs, rsmd.getColumnType(i), rsmd.getColumnName(i))); } System.out.println("-----------"); } prestmt.close(); conn.close(); } //更新 public static void updateTest()throws Exception{ Connection conn=getConnection(); Statement stmt=conn.createStatement(); String sql="update jdbc_student set name='李四散步吧' where id='2'"; int result=stmt.executeUpdate(sql); System.out.println(result); stmt.close(); conn.close(); } //删除 public static void delTest()throws Exception{ Connection conn=getConnection(); Statement stmt=conn.createStatement(); String sql="delete jdbc_student where id='2'"; int result=stmt.executeUpdate(sql); System.out.println(result); stmt.close(); conn.close(); }
//uuid生成方法 public static String getUUID() { return UUID.randomUUID().toString().replace("-", ""); } //获取object的值 public static Object getValue(ResultSet rs, int type, String columnName)throws SQLException { //type为java.sql.Types的具体对应值 if (type == 4) {// integer类型 return rs.getInt(columnName); } else if (type == 12) {// varchar2类型 return rs.getString(columnName); } else if (type == 91) {// date类型 return rs.getDate(columnName); } return null; } }
表结构的数据类型如下:
上面获取object的值的方法,这个type为java.sql.Types的具体对应值,具体的数值见下面:
//java.sql.Types具体值 public final static int BIT = -7; public final static int TINYINT = -6; public final static int SMALLINT = 5; public final static int INTEGER = 4; public final static int BIGINT = -5; public final static int FLOAT = 6; public final static int REAL = 7; public final static int DOUBLE = 8; public final static int NUMERIC = 2; public final static int DECIMAL = 3; public final static int CHAR = 1; public final static int VARCHAR = 12; public final static int LONGVARCHAR = -1; public final static int DATE = 91; public final static int TIME = 92; public final static int TIMESTAMP = 93; public final static int BINARY = -2; public final static int VARBINARY = -3; public final static int LONGVARBINARY = -4; public final static int NULL = 0; public final static int OTHER = 1111; public final static int JAVA_OBJECT = 2000; public final static int DISTINCT = 2001; public final static int STRUCT = 2002; public final static int ARRAY = 2003; public final static int BLOB = 2004; public final static int CLOB = 2005; public final static int REF = 2006; public final static int DATALINK = 70; public final static int BOOLEAN = 16; public final static int ROWID = -8; public static final int NCHAR = -15; public static final int NVARCHAR = -9; public static final int LONGNVARCHAR = -16; public static final int NCLOB = 2011; public static final int SQLXML = 2009; [color=blue][/color][size=large][/size]
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