tonglin0325的个人主页

SpringBoot学习笔记——swagger-ui

tonglin0325

swagger-ui用于给API添加文档，还支持API的请求调用，可以降低前后端联调的沟通成本

1.依赖

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<!-- swagger2 -->
<dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-swagger2</artifactId>
    <version>2.8.0</version>
</dependency>
<dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-swagger-ui</artifactId>
    <version>2.8.0</version>
</dependency>

2.配置swagger，注意修改basePackage成实际的包名

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import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.context.request.async.DeferredResult;
import springfox.documentation.builders.ApiInfoBuilder;
import springfox.documentation.builders.PathSelectors;
import springfox.documentation.builders.RequestHandlerSelectors;
import springfox.documentation.service.ApiInfo;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spring.web.plugins.Docket;
import springfox.documentation.swagger2.annotations.EnableSwagger2;

@Configuration
@EnableSwagger2
public class SwaggerConfig {

    @Bean
    public Docket createRestApi() {
        return new Docket(DocumentationType.SWAGGER_2)
                .genericModelSubstitutes(DeferredResult.class)
                .useDefaultResponseMessages(false)
                .forCodeGeneration(true)
                .apiInfo(apiInfo())
                .pathMapping("/") // base，最终调用接口后会和paths拼接在一起
                .select()
                .apis(RequestHandlerSelectors.basePackage("com.example.demo")) // 过滤的接口
                .paths(PathSelectors.any())
                .build();
    }

    private ApiInfo apiInfo() {
        return new ApiInfoBuilder()
                .title("api文档") // 标题
                .description("xxxx") // 描述
                .termsOfServiceUrl("https://xxx.xxx.xxx")
                .version("1.0")
                .build();
    }

}

3.给controller添加 ApiOperation 注解

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@ApiOperation(value = "hello接口", notes = "取得id，打印hello")
@RequestMapping(path = "/hello/{id}", method = RequestMethod.GET)
public ControllerResponseT hello(@ApiParam(name = "id", value = "id", required = true) @PathVariable("id") Integer id) {
return ControllerResponseT.ofSuccess("hello: " + id);
}

4.测试

全文 >>

Java——组件：标签组件，文本组件，菜单组件，表格组件，按钮组件

tonglin0325

 

 

使用一个标签

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import java.awt.Color;
import java.awt.Dimension;
import java.awt.Point;

import javax.swing.JFrame;
import javax.swing.JLabel;

public class JFrame_demo {

	public static void main(String[] args) {
		// TODO 自动生成的方法存根
		
		JFrame f = new JFrame("Swing窗口");							//实例化窗体对象
		JLabel lab = new JLabel("Label",JLabel.CENTER);		//实例化对象，使用剧中对齐
		f.add(lab);																				//向容器中加入组建
		Dimension dim = new Dimension();								//实例化Dimension对象
		
		dim.setSize(230,80);			//设置大小
		f.setSize(dim);						//设置组件大小
		f.setBackground(Color.WHITE);
		Point point = new Point(300,200);		//设置现实的坐标点
		f.setLocation(point);
		f.setVisible(true);
	}

}

 

 

更改JLabel的文本样式

 

设置标签的显示字体、大小、背景颜色

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import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Point;

import javax.swing.JFrame;
import javax.swing.JLabel;

public class JFrame_demo {

	public static void main(String[] args) {
		// TODO 自动生成的方法存根
		
		JFrame f = new JFrame("Swing窗口");							//实例化窗体对象
		JLabel lab = new JLabel("Label",JLabel.CENTER);		//实例化对象，使用剧中对齐
		Font fnt = new Font("Serief",Font.ITALIC+Font.BOLD,28);
		lab.setFont(fnt); 									//设置标签的显示字体
		lab.setForeground(Color.RED); 	//设置标签的文字颜色
		f.add(lab);																				//向容器中加入组建
		Dimension dim = new Dimension();								//实例化Dimension对象
		
		dim.setSize(230,80);			//设置大小
		f.setSize(dim);						//设置组件大小
		f.setBackground(Color.WHITE);
		Point point = new Point(300,200);		//设置现实的坐标点
		f.setLocation(point);
		f.setVisible(true);
	}

}

 

 

全文 >>

Java数据库——PreparedStatement接口

tonglin0325

PreparedStatement接口是Statement的子接口，属于预处理操作，与直接使用Statement不同的是，PreparedStatement在操作时，是先在数据表中准备好了一条SQL语句，但是此SQL语句的具体内容暂时不设置，而是之后再进行设置。

 

使用PreparedStatement完成数据的增加和查询操作

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import java.sql.*;
import java.text.SimpleDateFormat;

public class PreparedStatement_demo {

	//定义MySQL的数据库驱动程序
	public static final String DBDRIVER = "org.gjt.mm.mysql.Driver";
	//定义MySQL数据库的连接地址
	public static final String DBURL = "jdbc:mysql://localhost:3306/mysql_demo";
	//MySQL数据库的连接用户名
	public static final String DBUSER = "root";
	//MySQL数据库的连接密码
	public static final String DBPASS = "123456";
	
	public static void main(String[] args) throws Exception{
		// TODO 自动生成的方法存根
		Connection conn = null;						//数据库连接
		PreparedStatement pstmt = null;	//数据库操作
		
		String name = "王五";
		String password = "pwd2";
		int age = 25;
		String sex = "女";
		String birthday = "2002-11-21";
		java.util.Date temp = null;				//声明一个Date对象
		//通过SimpleDateFormat类将一个字符串变成java.util.Date类型
		temp = new SimpleDateFormat("yyyy-MM-dd").parse(birthday);
		//通过java.util.Date取出具体的日期数，并将其变成java.sql.Date类型
		java.sql.Date bir = new java.sql.Date(temp.getTime());
		String sql = "INSERT INTO user(name,password,age,sex,birthday)"+"VALUES(?,?,?,?,?)";//编写预处理SQL
		Class.forName(DBDRIVER);			//加载驱动程序
		//连接MySQL数据库时，要写上连接的用户名和密码
		conn = DriverManager.getConnection(DBURL,DBUSER,DBPASS);
		pstmt = conn.prepareStatement(sql);		//实例化PreparedStatement
		pstmt.setString(1, name);					//设置第一个&ldquo;？&rdquo;的内容
		pstmt.setString(2, password);			//设置第二个&ldquo;？&rdquo;的内容
		pstmt.setInt(3, age);								//设置第三个&ldquo;？&rdquo;的内容
		pstmt.setString(4, sex);							//设置第四个&ldquo;？&rdquo;的内容
		pstmt.setDate(5, bir);							//设置第五个&ldquo;？&rdquo;的内容
		pstmt.executeUpdate();						//执行数据库更新操作，不需要SQL
		
		pstmt.close(); 										//操作关闭
		conn.close(); 										//数据库关闭
		
	}

}

 

模糊查询

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import java.sql.*;
import java.text.SimpleDateFormat;

public class PreparedStatement_demo {

	//定义MySQL的数据库驱动程序
	public static final String DBDRIVER = "org.gjt.mm.mysql.Driver";
	//定义MySQL数据库的连接地址
	public static final String DBURL = "jdbc:mysql://localhost:3306/mysql_demo";
	//MySQL数据库的连接用户名
	public static final String DBUSER = "root";
	//MySQL数据库的连接密码
	public static final String DBPASS = "123456";
	
	public static void main(String[] args) throws Exception{
		// TODO 自动生成的方法存根
		
		Connection conn = null;						//数据库连接
		PreparedStatement pstmt = null;	//数据库操作
		String keyWord = "王";							//设置查询关键字
		String keyWord1 = "男";							//设置查询关键字
		ResultSet rs = null;								//保存查询结果
		String sql = "SELECT id,name,password,age,sex,birthday"+
				" FROM user WHERE name LIKE ? OR password LIKE ? OR sex LIKE ?";
		Class.forName(DBDRIVER);			//加载驱动程序
		//连接MySQL数据库时，要写上连接的用户名和密码
		conn = DriverManager.getConnection(DBURL,DBUSER,DBPASS);
		pstmt = conn.prepareStatement(sql);		//实例化PreparedStatement
		pstmt.setString(1, "%"+keyWord+"%");					//设置第一个&ldquo;？&rdquo;的内容
		pstmt.setString(2, "%"+keyWord+"%");					//设置第一个&ldquo;？&rdquo;的内容
		pstmt.setString(3, "%"+keyWord1+"%");					//设置第一个&ldquo;？&rdquo;的内容
		rs = pstmt.executeQuery();						//实例化ResultSet对象
		while(rs.next()){
			int id = rs.getInt(1);
			String name = rs.getString(2);
			String pass = rs.getString(3);
			int age = rs.getInt(4);
			String sex = rs.getString(5);
			java.util.Date d = rs.getDate(6);
			System.out.println("编号："+id);
			System.out.println("名字："+name);
			System.out.println("密码："+pass);
			System.out.println("年龄："+age);
			System.out.println("性别："+sex);
			System.out.println("生日："+d);
		}
		rs.close();												//关闭结果集
		pstmt.close(); 										//操作关闭
		conn.close(); 										//数据库关闭
		
	}

}

 

 

Java数据库——ResultSet接口

tonglin0325

使用SQL中的SELECT语句可以查询出数据库的全部结果，在JDBC的操作中数据库的所有查询记录将使用ResultSet进行接收，并使用ResultSet显示内容。

 

从user表中查询数据

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import java.sql.*;

public class MySQL_demo {
	//定义MySQL的数据库驱动程序
	public static final String DBDRIVER = "org.gjt.mm.mysql.Driver";
	//定义MySQL数据库的连接地址
	public static final String DBURL = "jdbc:mysql://localhost:3306/mysql_demo";
	//MySQL数据库的连接用户名
	public static final String DBUSER = "root";
	//MySQL数据库的连接密码
	public static final String DBPASS = "123456";
	
	public static void main(String[] args) throws Exception {
		// TODO 自动生成的方法存根
		
		Connection conn = null;					//数据库连接
		Statement stmt = null;					//数据库操作
		
		ResultSet rs = null;			//保存查询结果
		String sql = "SELECT id,name,password,age,sex,birthday FROM user";
		Class.forName(DBDRIVER);			//加载驱动程序
		//连接MySQL数据库时，要写上连接的用户名和密码
		conn = DriverManager.getConnection(DBURL,DBUSER,DBPASS);
		stmt = conn.createStatement();		//实例化Statement对象
		rs = stmt.executeQuery(sql);			//实例化ResultSet对象
		while(rs.next()){
//			int id = rs.getInt("id");
//			String name = rs.getString("name");
//			String pass = rs.getString("password");
//			int age = rs.getInt("age");
//			String sex = rs.getString("sex");
//			Date d = rs.getDate("birthday");
			int id = rs.getInt(1);
			String name = rs.getString(2);
			String pass = rs.getString(3);
			int age = rs.getInt(4);
			String sex = rs.getString(5);
			Date d = rs.getDate(6);
			System.out.println("编号："+id);
			System.out.println("名字："+name);
			System.out.println("密码："+pass);
			System.out.println("年龄："+age);
			System.out.println("性别："+sex);
			System.out.println("生日："+d);
		}
		
		rs.close(); 												//关闭结果集
		stmt.close(); 										//操作关闭
		conn.close(); 										//数据库关闭
	}
}

 

Java数据库——连接关闭、增删改查

tonglin0325

连接数据库

 

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import java.sql.*;

public class MySQL_demo {
	//定义MySQL的数据库驱动程序
	public static final String DBDRIVER = "org.gjt.mm.mysql.Driver";
	//定义MySQL数据库的连接地址
	public static final String DBURL = "jdbc:mysql://localhost:3306/mysql_demo";
	//MySQL数据库的连接用户名
	public static final String DBUSER = "root";
	//MySQL数据库的连接密码
	public static final String DBPASS = "123456";
	
	public static void main(String[] args) {
		// TODO 自动生成的方法存根
		Connection conn = null;					//数据库连接
		try{
			Class.forName(DBDRIVER);		//加载MYSQL JDBC驱动程序
		}catch(ClassNotFoundException e){
			e.printStackTrace();
		}
		try{
			//连接MySQL数据库时，要写上连接的用户名和密码
			conn = DriverManager.getConnection(DBURL,DBUSER,DBPASS);
		}catch(SQLException e){
			e.printStackTrace();
		}
		System.out.println(conn);
		try{
			conn.close(); 				//数据库关闭
		}catch(SQLException e){
			e.printStackTrace();
		}
	}
}

 

建立一个user表

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CREATE TABLE user(id INT PRIMARY KEY AUTO_INCREMENT,name VARCHAR(30) NOT NULL,password VARCHAR(32) NOT NULL,age INT NOT NULL,sex VARCHAR(2),birthday DATE);

 

<1>数据库的更新操作

 

执行数据库插入操作，执行一次插入一条

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import java.sql.*;

public class MySQL_demo {
	//定义MySQL的数据库驱动程序
	public static final String DBDRIVER = "org.gjt.mm.mysql.Driver";
	//定义MySQL数据库的连接地址
	public static final String DBURL = "jdbc:mysql://localhost:3306/mysql_demo";
	//MySQL数据库的连接用户名
	public static final String DBUSER = "root";
	//MySQL数据库的连接密码
	public static final String DBPASS = "123456";
	
	public static void main(String[] args) throws Exception {
		// TODO 自动生成的方法存根
		
		Connection conn = null;					//数据库连接
		Statement stmt = null;					//数据库操作
		String sql = "INSERT INTO user(name,password,age,sex,birthday)"
				+"VALUES('张三','mima',30,'男','2014-01-11')";
		Class.forName(DBDRIVER);			//加载驱动程序
		//连接MySQL数据库时，要写上连接的用户名和密码
		conn = DriverManager.getConnection(DBURL,DBUSER,DBPASS);
		stmt = conn.createStatement();		//实例化Statement对象
		stmt.executeUpdate(sql);				//执行数据库更新操作
		stmt.close(); 										//操作关闭
		conn.close(); 										//数据库关闭
	}
}

全文 >>

Avro学习笔记——avro-tools工具

tonglin0325

1.下载avro-tools.jar

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https://archive.apache.org/dist/avro/avro-1.10.1/java/

avro-tools.jar常用命令：Working with Apache Avro files in Amazon S3　　

也可以查看help

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java -jar ./avro-tools-1.10.1.jar help
Version 1.10.1 of Apache Avro
Copyright 2010-2015 The Apache Software Foundation

This product includes software developed at
The Apache Software Foundation (https://www.apache.org/).
----------------
Available tools:
    canonical  Converts an Avro Schema to its canonical form
          cat  Extracts samples from files
      compile  Generates Java code for the given schema.
       concat  Concatenates avro files without re-compressing.
        count  Counts the records in avro files or folders
  fingerprint  Returns the fingerprint for the schemas.
   fragtojson  Renders a binary-encoded Avro datum as JSON.
     fromjson  Reads JSON records and writes an Avro data file.
     fromtext  Imports a text file into an avro data file.
      getmeta  Prints out the metadata of an Avro data file.
    getschema  Prints out schema of an Avro data file.
          idl  Generates a JSON schema from an Avro IDL file
 idl2schemata  Extract JSON schemata of the types from an Avro IDL file
       induce  Induce schema/protocol from Java class/interface via reflection.
   jsontofrag  Renders a JSON-encoded Avro datum as binary.
       random  Creates a file with randomly generated instances of a schema.
      recodec  Alters the codec of a data file.
       repair  Recovers data from a corrupt Avro Data file
  rpcprotocol  Output the protocol of a RPC service
   rpcreceive  Opens an RPC Server and listens for one message.
      rpcsend  Sends a single RPC message.
       tether  Run a tethered mapreduce job.
       tojson  Dumps an Avro data file as JSON, record per line or pretty.
       totext  Converts an Avro data file to a text file.
     totrevni  Converts an Avro data file to a Trevni file.
  trevni_meta  Dumps a Trevni file's metadata as JSON.
trevni_random  Create a Trevni file filled with random instances of a schema.
trevni_tojson  Dumps a Trevni file as JSON.

2.查看avro文件的schema

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java -jar ./avro-tools-1.10.1.jar getschema ./xxxx.avro

3.查看avro文件内容的json格式

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java -jar ./avro-tools-1.10.1.jar tojson ./nova_ads_access_log-0-0008589084.avro | less

4.使用avro-tools编译java代码

编译avro IDL文件，参考

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https://yanbin.blog/convert-apache-avro-to-parquet-format-in-java/

定义schema文件kst.avsc

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{
  "namespace": "com.linkedin.haivvreo",
  "name": "test_serializer",
  "type": "record",
  "fields": [
    { "name":"string1", "type":"string" },
    { "name":"int1", "type":"int" },
    { "name":"tinyint1", "type":"int" },
    { "name":"smallint1", "type":"int" },
    { "name":"bigint1", "type":"long" },
    { "name":"boolean1", "type":"boolean" },
    { "name":"float1", "type":"float" },
    { "name":"double1", "type":"double" },
    { "name":"list1", "type":{"type":"array", "items":"string"} },
    { "name":"map1", "type":{"type":"map", "values":"int"} },
    { "name":"struct1", "type":{"type":"record", "name":"struct1_name", "fields": [
          { "name":"sInt", "type":"int" }, { "name":"sBoolean", "type":"boolean" }, { "name":"sString", "type":"string" } ] } },
    { "name":"union1", "type":["float", "boolean", "string"] },
    { "name":"enum1", "type":{"type":"enum", "name":"enum1_values", "symbols":["BLUE","RED", "GREEN"]} },
    { "name":"nullableint", "type":["int", "null"] },
    { "name":"bytes1", "type":"bytes" },
    { "name":"fixed1", "type":{"type":"fixed", "name":"threebytes", "size":3} }
  ] }

全文 >>

Impala学习笔记——impala shell

tonglin0325

进入impala shell，port为Impala Daemon Beeswax 端口

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impala-shell -i ip:port -k

使用impala shell直接运行SQL

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impala-shell -i ip:port -k --quiet -B -d default -q "select count(*) from table1 where ds='2021-01-20'"

退出

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exit;

 

Ubuntu下的MySQL安装

tonglin0325

1.安装mysql-server

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sudo apt-get update
sudo apt-get install mysql-server mysql-client

2.重新启动mysql服务

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sudo service mysql restart

3.让apache支持mysql

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sudo apt-get install libapache2-mod-auth-mysql

16.04使用下面命令

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sudo apt-get install libmysqlclient-dev

4.登录mysql

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mysql -u root -p

如果修改了配置文件my.cnf配置文件，需要重启数据库（修改方法在下面），重启数据库之前需要先重新载入apparmor配置文件，使用下面命令重新载入：

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sudo /etc/init.d/apparmor restart

重新启动数据库

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sudo /etc/init.d/mysql start

5.查看数据库的编码

1.查看MySQL数据库服务器和数据库MySQL字符集。

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SHOW VARIABLES LIKE 'character_set_%';

 

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元注解(Annotation)

tonglin0325

J2SE 5.0提供了很多新的特征。其中一个很重要的特征就是对元数据(Metadata)的支持。在J2SE 5.0中，这种元数据称为注解(Annotation)。

通过使用注解，程序开发人员可以在不改变原有逻辑的情况下，在源文件嵌入一些补充的信息。

 

系统内建的Annotation

在JDK1.5之后，系统已经建立了如下3个内建的Annotation类型，用户直接使用即可。

 

@Override

 

 

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tonglin0325

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