In Tridion Deployer extension (Java), I am able to get the Component Presentation data, but it is in compressed format as my templates are in DD4T.
Can any one help me how to decompress the Component fields data?
Simplest solution would be not to compress the JSON in your Templates, then you also wouldn't have to deal with decompression. This is done by removing the compression TBB from the Template.
Another option is to use the DD4T
org.dd4t.core.util.CompressionUtils to decompress it. See https://github.com/dd4t/dd4t-2-java/blob/develop/dd4t-core/src/main/java/org/dd4t/core/util/CompressionUtils.java