Eclipse Import Maven project appears red exclamation mark

Resolve Maven project with red exclamation mark

After importing the MAVEN project, you will see a red exclamation mark in the project, and first look at the error in Eclipse's problems, which is usually the missing jar package in the warehouse path to MAVEN, producing the reason:
Because some maven managed jars are not downloaded correctly.
The problematic jar is due to the fact that the current MAVEN repository cannot be found, so you can add a Maven repository that can find the appropriate jar in the following ways:

1. Search for the jar directly in Google, for example: Jmxri-1.2.1.jar

2. Find the MAVEN repository with this jar in the search results and add it to setting.xml.

3. Re-right-maven-update project.

Question 1: The above is Baidu to find out the method, but I found in the project Maven warehouse already exists the jar package, and the project to the Pom file is also the correct reference, but why still error?

Baidu for a long time, found that are some nonsense, and finally found a guy said that the jar has been damaged, so I use the compression tool to open, sure enough, the jar package is damaged in the download process, so the jar package is invalid, re-download.

Issue 2: Problem 1 solved, found or error Missing..................,jar package has already existed, and there is no damage, and went to Baidu for a long time, need to re-project right-click-maven-update Project. or error, not resolved, re-find the jar in the MAVEN repository path in addition to the jar package to delete files, and then right-maven-update project, finally solved the