Case The JRE version is too low to cause Eclipse to install PDT failed

Problem description: Using eclipse PDT's All-in-one package to build the eclipse PDT development environment, download and extract the All-in-one package,
Running eclipse does not appear in the PHP perspective.
The resolution process is as follows:
1 in accordance with the "Common Problems" proposal on the Eclipse website, running Eclipse-clean to start Eclipse is invalid.
2 attempt to delete the Eclipse/configuration/org.eclipse.update directory, let Eclipse refresh the configuration, invalid.
3) re-download and use other versions of the All-in-one package, invalid.

4 Final Solution: Through Eclipse "help"-> "About Eclipse platform"-> "Configuration Details"
-> "View error Log" and then with Google search error prompted the "Eclipse unsupported Major.minor version 49.0", found to be the JRE version of the bottom caused,
Eclipse requires the use of JRE5, and I am installing JRE1.4.2. The problem is solved after the replacement is JRE5.

In fact, the Eclipse download page recommended the use of JRE5, and I was accustomed to 1.4.2 so did not adopt the proposal, walk long way ...