caj格式的文件需要CAJViewer軟件才能打開，直接下載安裝壹個CAJViewer軟件，就可以將文件打開了。方法如下：
1、在瀏覽器搜索框輸入CAJViewer，然後點擊中國知網的這壹個搜索結果。
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2、進入中國知網之後，將CAJViewer下載到電腦上。
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3、然後找到剛剛下載的文件，雙擊將文件進行安裝。
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4、安裝成功之後點擊完成就可以了。
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5、然後找到需要打開的caj格式的文件，直接將它打開即可。
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註意事項：
caj格式的文件壹般是學術類的文件，可以直接在中國知網下載此軟件。