Category Archives: How to Fix

java.lang.NoSuchMethodError Quote: javax.servlet.com Yeah. HttpServletRequest.isAsyncStarted ()Z

When developing jetty 9 embedded system, it starts normally, but when browsing the page, an error is reported as follows:

java.lang.NoSuchMethodError : javax.servlet.http . HttpServletRequest.isAsyncStarted () Z
reason: jetty 9 relies on servlet API version 3. X. if other third-party open source libraries in the project implicitly rely on servlet API version 2. X, this error will be reported.
Reprinted: https://www.cnblogs.com/yjmyzz/p/5090990.html

Parsing double quotation marks with JSON

Parse a JSON data:

{“manifest”:{ Version:“3.0”}}

If you look carefully, this string is not in the normal JSON format. Version lacks double quotation marks. It should be:

{“manifest”:{ “Version”: “3.0”}}

Reprinted: https://www.cnblogs.com/afluy/p/4023838.html

If used

JSONObject mainfestObject.getJSONObject (“manifest”);

This method analysis will report an error, but if you use

String mainfestStr = object.optString (“manifest”, “”);

JSONObject mainfestObject = new JSONObject(mainfestStr);

The above method is successful!

Eclipse flash back does not open the problem

At first, I saw more than n solutions on the Internet. Unfortunately, I tried them all, but none of them solved my problem. Later, I tossed around and deleted the. Eclipse (click eclipse) in my C disk. After that, I rerun eclipse. After a while, I can start eclipse normally. Through this warning, I can’t quit eclipse abnormally

NuxtSe rverError:Request failed With status code 500 my solution and thinking

catalog

1、 Source of the problem

2、 Solutions

3、 Solutions

4、 Summary

1、 Source of the problem

Usually using nuxt and deploying it online are normal, and occasionally 500 errors are reported one day;

Nuxt.js The operation ( NPM run dev ) reported the following error:

The server error log is as follows:

0|qiu  |  ERROR  Request failed with status code 500                           20:17:14
0|qiu  |   at createError (node_modules/axios/lib/core/createError.js:16:15)
0|qiu  |   at settle (node_modules/axios/lib/core/settle.js:18:12)
0|qiu  |   at IncomingMessage.handleStreamEnd (node_modules/axios/lib/adapters/http.js:201:11)
0|qiu  |   at IncomingMessage.emit (events.js:187:15)
0|qiu  |   at IncomingMessage.EventEmitter.emit (domain.js:441:20)
0|qiu  |   at endReadableNT (_stream_readable.js:1094:12)
0|qiu  |   at process._tickCallback (internal/process/next_tick.js:63:19)

2、 Solutions

500 status code: server internal error, unable to complete the request.

Generally speaking, this problem occurs when the server code fails

So the problem lies in the back end, check the interface

3、 Solutions

Annotate the code one by one, and find an interface error in the page, so that the problem can be solved after the back-end correction;

The error of the request interface is as follows (PHP in the background)

 

It’s a clumsy way to comment the code one by one. If you can, you can directly look at the network of the console to see the interface in error;

4、 Summary

because Nuxt.js It is a framework for server-side rendering. As long as an interface in the page reports an error and the server returns an error, the front-end display page will crash;

And an interface error, nuxt only returns 500 errors, can’t directly locate the problem, need to check one by one, hope nuxt is more and more powerful

 

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[solution] build vins and orb-slam based on opencv4

Scheme for regular substitution via VScode.
When encountering an incorrect version of OpenCV

    1. Find.

(find_package\(OpenCV).*

    1. Replace:

$1 REQUIRED)

    1. CV_GRAY2RGB
    1. Find:

CV_(.*GRAY[^)]*)

Replace:

cv::COLOR_$1

    1. CV_AA
  2. Replace:

CV_AA

    1. Replace:

cv::LINE_AA

    1. CV_CALIB_*
    1. Replace:

CV_(CALIB[^ ,)]*)

    1. Replace:

cv::$1

    1. CV_LOAD_IMAGE_UNCHANGED、CV_LOAD_IMAGE_GRAYSCALE
    1. Find:

CV_LOAD_IMAGE_([^ )]*)

    1. Replace:

cv::IMREAD_$1

    1. Most other issues, just add the header file
      1. chessboard.cc Error
      No such file or directory

#include<opencv/cv.h>：

#include <opencv2/imgproc/imgproc_c.h>
#include <opencv2/highgui/highgui_c.h>

The solution cannot be separated due to a special separator

Today, when dealing with text data, we encountered this kind of text matching with space and tab regularization, which did not work. Later, I asked my colleagues and found that “\ \ uf8f5” could be used to match.

Pending text:

A	abbr.安 
A-10IInone.美空军主力近距离空中支援攻击机，无愧为“坦克杀手”。
A-12none.夭折的美海军第一种隐形舰载攻击机。
A-4  none.54年服役的单座轻型舰载攻击机，现仍被多国使用。
A-6none.双座重型全天候舰载攻击机，主要用于低空突防，可进行核打击。
A-7IInone.离开沙场的单座亚音速攻击机，曾是美海空军主力。
A-OKnone.极好, 妙极, 完美的
A-Znone.无所不包的
A-boilern.原子反应器加热用的锅炉
A-bombn.原子弹
A-certificatenone.儿童不宜n.A级
A-controln.原子能管制
A-energyn.原子能
A-framen.金字塔形建筑物
A-lovelnone.英语学校里某一课程结束时举行的高深考试, 高深级考试及格
A-oneadj.第一等的, 第一流的
A-roadnone.A级公路, 主车道
A-siden.A面
A-testn.原子爆炸试验
A-weaponn.原子武器

Separation processing:

	public static void main(String[] args) throws Exception {
		String dic = util.Directory.GetAppPath("steamData") + "dic.txt.bak";
		BufferedReader br = util.MyFileTool.GetBufferReader(dic);
		while(br.ready()) {
			String line = br.readLine();
			String[] words = line.split("\\uf8f5");
			System.out.println("size: " + words.length);
			System.out.println(words[0]);
		}
		br.close();
	}

[save] Maven’s pom.xml Labeled xsi:schemaLocation Error report

The reason why Maven installs x is that Maven will generate a *. Lastupdated file for the jar file that can’t be downloaded. If it doesn’t kill the *. Lastupdated file, it won’t download the jar for you again. So, kill the *. Lastupdated guy and update it again

Original text: https://blog.csdn.net/qq_ 22843051/article/details/79765040

[reprint and save] MySQL does not set the primary key and uses the self growing ID method

MySQL can only have one auto growth field per table. This auto growth field can be used as a primary key or a non primary key. However, please note that when you use an auto growth field as a non primary key, you must add a unique index to it, otherwise the system will report an error. For example:

1. Set the auto grow field as the primary key.

create table t1 (id int auto_ increment Primary key,sid int);

2. Set the auto grow field to a non primary key. Note that the unique key must be added explicitly.

create table t2 (sid int primary key,id int auto_ increment Unique);

3. Set the auto growth field to a non primary key. If no unique index is added, an error will be reported * *, as shown in the following statement

create table t3 (sid int primary key,id int auto_ increment)。

MySQL is a relational database management system, developed by MySQL AB company of Sweden, which is a product of Oracle at present. MySQL is one of the most popular relational database management systems. In web application, MySQL is the best RDBMS (relational database management system) application software. MySQL is a kind of relational database management system. Relational database stores data in different tables instead of putting all data in a large warehouse, which increases the speed and flexibility. The SQL language used by MySQL is the most commonly used standardized language for accessing databases. MySQL software adopts dual authorization policy, which is divided into community version and commercial version. Because of its small size, fast speed, low total cost of ownership, especially the open source, MySQL is generally chosen as the website database for the development of small and medium-sized websites. Because of the excellent performance of its community version, it can form a good development environment with PHP and Apache

come from: https://zhidao.baidu.com/question/621026495899595372.html

java.lang.IllegalArgumentException : urlcoder exception resolution

Exception:

Exception in thread “main” java.lang.IllegalArgumentException : URLDecoder: Illegal hex characters in escape (%) pattern – For input string: “u9”
    at java.net.URLDecoder .decode( URLDecoder.java:194 )
    at com.hbzx.controller . PayResultController.main ( PayResultController.java:253 ）
reasons:

Java call URLDecoder.decode (STR, “UTF-8”); the main reason for throwing the above exception is that% is a special character in the URL and needs special escape,

Solution: replace the% sign in the string with% 25

solve:

 url = url.replaceAll("%(?![0-9a-fA-F]{2})", "%25");
   String urlStr = URLDecoder.decode(url, "UTF-8");

D-page address: https://blog.csdn.net/afgasdg/article/details/40304817

Maven invalid source release 11

I see that my JDK configuration is 8, and I feel that it’s OK. Later I found out that my JDK configuration is 8 pom.xml The file configuration is as follows:

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>11</source>
                    <target>11</target>
                    <encoding>utf-8</encoding>
                </configuration>
            </plugin>
        </plugins>
    </build>

Change 11 to 8, problem solved!!!