Test Development Series --java web

Key words

Static and dynamic resources
And cross-domain origin policy
- Homologous concept:
  - Protocol, domain names, the same port, said they homology.
  - Only the same-origin policy restrictions dom js to read and write data in other domains have been restricted, such as javascript, css, pictures and other static resource loading is still considered to be homologous.

learning target

java development environment to build
http protocol
Overview and Java web project creation

A Brief History of java

In 1995, SUN JAVA release
In 2009, Oracle announced the acquisition of Sun
In 2010, one of the co-founder of Java James Gosling resigned from Oracle * Company
In 2011, Java7 officially released
2014, released the official version Java8

jdk- download and install

JDK to version 13, currently still the most used JDK8

Jdk8 download the installation files to a local
https://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html
Installation and configuration environment variable

Features java-

Java is a write once run everywhere, cross-platform
java virtual machine JVM, running bytecode .class
java is aObject-OrientedProgramming language, classes and objects
stack, heap, area method, runtime constant pool

eclipse installation

Eclipse is an open source, Java-based extensible development platform. The official version of Eclipse is an integrated development environment (IDE).
Decompression that is installed
Configuration jre

http protocol

Hypertext Transfer Protocol, Hypertext Transfer Protocol
"Communicate" is the norm between the browser and server
http are "application layer protocol", TCP / IP-based protocol
http stateless protocol

HTTP1.0 request defines three methods:GET, POSTAnd HEAD methods.
HTTP1.1 five new request method: OPTION,PUT, DELETE, TRACE and CONNECT method.

http1.1 configuration protocol request message

A http request complete message, comprising a request line, a plurality of message header (request header), line feed, solid content

http1.1 protocol response message structure

In response to data representative of a http server will send the client, which includes a status line, a plurality of headers, and an empty row, the entity content.

HTTP status code

The Status Code the HTTP
1xx: indication information - indicates a request has been received, processing continues
2xx: Success - indicates that the request has been successfully received, understood, accepted
3xx: Redirection - to fulfill the request must be carried out further operations
4xx: Client Error - Request syntax error or a request can not be achieved
5xx: server-side error - the server failed to achieve a legitimate request

Common status codes:
The OK 200 is
201 ...... (to be added)

REST

REST (Representational State Transfer): Representational State Transfer
If a REST framework in line with the principle of the call Restful architecture, lightweight, cross-platform, cross-language design;

Based url HTTP protocol: https: //ke.qq.com/course/402016

GET (SELECT): Remove the resource from the server (one or more).
POST (CREATE): a new resource on the server.
PUT (UPDATE): update the resource (after the complete resources provided by the client to change) in the server.
PATCH (UPDATE): Updating Resource (provided by the client to change the properties) in the server.
DELETE (DELETE): Delete the resource from the server.

Java Web

Java Web, Java technology is used to solve the sum of the areas of technology-related web Internet.
web include: web server and web client in two parts. Now the browser can be used as a client, the ability to develop server-side.
Technology: servlet, jsp, tomcat
New web project in eclipse

Exercise 1: java basic algorithm

A binary search run results screenshot

TestSearch.java dichotomy lookup code

public class TestSearch {

       public static void main(String[] args) {
           int[] arr = new int[] { 11, 22, 33, 45, 66, 67, 77, 88, 90 };
           System.out.println(search(arr, 11));
           System.out.println(search(arr, 45));
           System.out.println(search(arr, 67));
           System.out.println(search(arr, 88));
           System.out.println(search(arr, 99));
       }

       public static int search(int[] arr, int key) {
           int start = 0;
           int end = arr.length - 1;
           while (start <= end) {
               int middle = (start + end) / 2;
               if (key < arr[middle]) {
                   end = middle - 1;
               } else if (key > arr[middle]) {
                   start = middle + 1;
               } else {
                   return middle;
               }
           }
           return -1;
       }
}

Bubble algorithm run results screenshot

BubbleSort.java bubble algorithm code

public class BubbleSort {

  public static void main(String[] args) {
    int[] array={2,8,9,1,10,31,0};
    getSortD_X(array);
    getSortX_D(array);
  }
  public static void getSortD_X(int[] array){
    for (int i = 0; i < array.length; i++) {
      for(int j=0;j<array.length-1;j++){
        if(array[i]>array[j]){
          int temp=array[i];
          array[i]=array[j];
          array[j]=temp;
        }
      }
    }
    System.out.print("从大到小：");
    for (int i = 0; i < array.length; i++) {
      if(i==array.length-1){
        System.out.println(array[i]);
      }else{
        System.out.print(array[i]+",");
      }
    }
  }
  public static void getSortX_D(int[] array){
    for (int i = 0; i <array.length; i++) {
      for(int j=0;j<array.length-i-1;j++){
        if(array[j]>array[j+1]){
          int temp=array[j];
          array[j]=array[j+1];
          array[j+1]=temp;
        }
      }
    }
    System.out.print("从小到大：");
    
    for (int i = 0; i < array.length; i++) {
      if(i==array.length-1){
        System.out.println(array[i]);
      }else{
        System.out.print(array[i]+",");
      }
    }
  }
}

Exercise 2: Building the java web project to write a servlet

Screenshot operating results

Project Screenshot

HelloWeb.java Code

package com.one.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class HelloWeb
 */
@WebServlet("/HelloWeb")
public class HelloWeb extends HttpServlet {
  private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public HelloWeb() {
        super();
    }

  /**
   * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
   */
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.getWriter().append("Served at: ").append(request.getContextPath());
    PrintWriter pw = response.getWriter();
    pw.print("hello world");
  }

  /**
   * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
   */
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    doGet(request, response);
  }
}

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