http断点续传简单实现（java)

/* nJ" '  
**SiteFileFetch.java \w'*z&`W9  
*/ sdS^e`S  
package NetFox; ,~?YBLw@c  
import java.io.*; RN@ctRS  
import java.net.*; h
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public class SiteFileFetch extends Thread { Ka,^OW}<%q  
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SiteInfoBean siteInfoBean = null; //文件信息Bean [}fv  dW  
long[] nStartPos; //开始位置 aj}(E+  
long[] nEndPos; //结束位置 1@lJonlF  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 :\=CRaA  
long nFileLength; //文件长度 vp.ZK[/`  
boolean bFirst = true; //是否第一次取文件 r:]1O*  
boolean bStop = false; //停止标志 *cO sv  
File tmpFile; //文件下载的临时信息 B^^r\L9  
DataOutputStream output; //输出到文件的输出流 K5"#~\D  
)*:`':_a  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） Dwl3Cj  
public SiteFileFetch(SiteInfoBean bean) throws IOException >,DbNmi  
{ (L`j0kPN  
siteInfoBean = bean; ;m2<eS`o'  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); rSYi<ku  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); BT@r!>Nl  
if(tmpFile.exists ()) #:d =)Qj0  
{ r$wxk 4%Rz  
bFirst = false; ~gu3g^<0v  
read_nPos(); TB;o~>9U  
} 0VK-g}"x  
else _FwK-?4E-  
{ uWrQ&}@  
nStartPos = new long[bean.getNSplitter()]; XbQlHfrS  
nEndPos = new long[bean.getNSplitter()]; FW.$5*f='  
} EJ`T$JD  
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} -Qn=|2Mm?  
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public void run() 8?FbtBAn  
{ HQ{JwW!m  
//获得文件长度 ^S6u<,  
//分割文件 PpsIhMq@  
//实例FileSplitterFetch @ps1Dr4s  
//启动FileSplitterFetch线程 1 tR_8lC  
//等待子线程返回 C^)
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try{ (os$B  
if(bFirst) zuJtpMn  
{ YA&g$
!  
nFileLength = getFileSize(); > 0<)=  
if(nFileLength == -1) CZbYAxNl  
{ :EHJ\+kejX  
System.err.println("File Length is not known!"); N&[D>
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} |_G )qp;  
else if(nFileLength == -2) RV&^g*;E  
{ cr;g5C V  
System.err.println("File is not access!"); )3(;tT,$}^  
} #M!!CX*k  
else Iz[@^IUx=  
{ jM:Y'l]  
for(int i=0;i<nStartPos.length;i++) mYU9 trHV  
{ b]a@  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); "U\JV)N  
} p^iRPI  
for(int i=0;i<nEndPos.length-1;i++) RQFI'@Ks  
{ +<prgP`v  
nEndPos = nStartPos[i+1]; ;us%/kOR  
} ",)Qc!^P$  
nEndPos[nEndPos.length-1] = nFileLength; aTzjm`F0  
} !cGDy/|  
} jP~Z`yf  
rS1fK1dys  
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//启动子线程 RyRpl*^
 
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; Pm$q]A~  
for(int i=0;i<nStartPos.length;i++) I7&_Xr  
{ e${>#>  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), #Mg]GeDJ{  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), BYKoel  
nStartPos,nEndPos,i); zB? V_aT  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 0c
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fileSplitterFetch.start(); ,hVvve,j}  
} 3<F </  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), )(7&X45,k  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); =tU{7i*+  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 9h0X&1u  
nEndPos = " + nFileLength); wKH ::!  
// fileSplitterFetch[nPos.length-1].start(); M3~K,$@  
/cZ-tSC)o  
cT\I[9!)  
//等待子线程结束 _GKB6e%  
//int count = 0; ;=? ~ -_  
//是否结束while循环 & /4k7X}y  
boolean breakWhile = false; pMs AyCAk  
2r%lA\,h$  
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while(!bStop) F,5r9^,_  
{ [TCP-bU  
write_nPos(); $'pNp B#vH  
Utility.sleep(500); Va$Pi19 O  
breakWhile = true; -8N|xQ378  
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for(int i=0;i<nStartPos.length;i++) >{ me  
{ + S4fGT  
if(!fileSplitterFetch.bDownOver) Zatf9yGD  
{ qT/Do?Y  
breakWhile = false; ?b!Fa  
break; <|?K%FP7Z  
} dCu'>G\bP  
} _uc\ D R  
if(breakWhile) CDi<<,  
break; *UW=M
dt  
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?6!]Nl1gr  
//count++; dSCzx .c  
//if(count>4) }oJAB1'k  
// siteStop(); VB<Jf'NU  
} t!K*pM  
+\"-P72vjk  
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System.err.println("文件下载结束！");
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} Db"DG(  
catch(Exception e){e.printStackTrace ();} ;#MB7A  
} al+ #y)+  
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//获得文件长度 iE.-FZc  
public long getFileSize() )wVIb)`R>Y  
{ :SV>+EDY   
int nFileLength = -1; RmI1`  
try{ _owjTo}  
URL url = new URL(siteInfoBean.getSSiteURL()); ]B=C|usJ  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); >5G>D~b  
httpConnection.setRequestProperty("User-Agent","NetFox"); C!C|\$)-  
",>H(wJ8  
 Yav2q3  
int responseCode=httpConnection.getResponseCode(); dO7;}>F$n  
if(responseCode>=400) ?r_l8  
{ bw&myzs  
processErrorCode(responseCode);
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return -2; //-2 represent access is error YwcPX`eg  
} A$.fv5${  
//Ai.Q.J[  
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String sHeader; 3/JyUh?  
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for(int i=1;;i++) u-"
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{ -=698h*  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); htP|3B  
//Utility.log(in.readLine()); 1nPZ<^A&@  
sHeader=httpConnection.getHeaderFieldKey(i); w{ `|N$  
if(sHeader!=null) #0;HOeIiH  
{ j8 C8X$  
if(sHeader.equals("Content-Length")) _#o' +_Z  
{ }1-I[q6  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); z<]bv7V  
break; s=Q(C[%I  
} U/;]zdP.K  
} m=qOg>k  
else `Pc3?~>0HH  
break; R.s|j=  
} `P@- %T  
} ]IJv-(  
catch(IOException e){e.printStackTrace ();} mDFlz1J,e  
catch(Exception e){e.printStackTrace ();} Ri>?KrQF%  
`:M^8SYrL  
"8V{5e!%j'  
Utility.log(nFileLength); V,%L~dI  
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return nFileLength; N_75-S7Cm  
} #
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//保存下载信息（文件指针位置） mCKk*5ws5"  
private void write_nPos() H;WY!X$x  
{ ezTZnutZ  
try{ G[idN3+#  
output = new DataOutputStream(new FileOutputStream(tmpFile)); .]Mn^2#j  
output.writeInt(nStartPos.length); 7.bN99{xPM  
for(int i=0;i<nStartPos.length;i++) v[<Bjs\q5  
{ q;AT>" =)  
// output.writeLong(nPos); P,bd'  
output.writeLong(fileSplitterFetch.nStartPos); !.fw,!}hOD  
output.writeLong(fileSplitterFetch.nEndPos); `"k9wC1  
} 6@4n'w{"  
output.close(); `#IcxweA  
} |d
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catch(IOException e){e.printStackTrace ();} V:bV ?lt  
catch(Exception e){e.printStackTrace ();} |Y_ -  
} `0#H]=$2h  
:46h+?   
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//读取保存的下载信息（文件指针位置） !F!3Q4  
private void read_nPos() :u%$0p>  
{ >CgO<\  
try{ \|Dei);k  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); GO5~!g  
int nCount = input.readInt(); _>bRv+RVR  
nStartPos = new long[nCount]; TA}UY7v  
nEndPos = new long[nCount]; EEf ]u7  
for(int i=0;i<nStartPos.length;i++) R_Dc)  
{ )"O{D`uX  
nStartPos = input.readLong(); 6&2LWaWMo$  
nEndPos = input.readLong(); ;)!"Ty|  
} G5]1s  
input.close(); 9
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} KO]N%]:&~  
catch(IOException e){e.printStackTrace ();} w\|Ei(  
catch(Exception e){e.printStackTrace ();} i~qfGl p6)  
} .6T6 S v  
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private void processErrorCode(int nErrorCode) zXc}W*ymj  
{ B!aK  
System.err.println("Error Code : " + nErrorCode);  YRB%:D@u  
} Fm j=  
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6*1$8G`$8,  
//停止文件下载 _py2kjA6  
public void siteStop() 0kCQ0xB[a5  
{ J+<p+(^*v  
bStop = true; T%CxvZ  
for(int i=0;i<nStartPos.length;i++) [5pCL0<c@  
fileSplitterFetch.splitterStop(); W7G9Kx1Y  
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9}.}Hd  
} 'UDBV  
} r25Z`X Z  
//负责部分文件的抓取 E;-qP)yU  
**FileSplitterFetch.java xDrV5bg
 
*/ 4u:0n>nJ1  
package NetFox; #7z|mVzH  
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import java.io.*; <Dw]yGK@  
import java.net.*; 6`puTL?  
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public class FileSplitterFetch extends Thread { u2qV6/  
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String sURL; //File URL j|'R$|  
long nStartPos; //File Snippet Start Position {},;-%xE  
long nEndPos; //File Snippet End Position Q(\ wx
 
int nThreadID; //Thread's ID ,8SWe  
boolean bDownOver = false; //Downing is over l`rC0kJ]  
boolean bStop = false; //Stop identical XNmQ?`.2'  
FileAccessI fileAccessI = null; //File Access interface +0#JnqH"  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException F2oJ]th.3  
{ <%,'$^'DS  
this.sURL = sURL; X!0kK8v  
this.nStartPos = nStart; VJ1*|r,  
this.nEndPos = nEnd; q`loOm=y  
nThreadID = id; :Ee?K  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 ],?pe  
} .98.G4J>  
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public void run() (UW6F4:$  
{ ( Yi=v'd  
while(nStartPos < nEndPos && !bStop) ^]rxhpS  
{ u_'nOle K  
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try{ H'Iq~Ft1  
URL url = new URL(sURL); HU[oR4E  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); |9]PtgQv7  
httpConnection.setRequestProperty("User-Agent","NetFox"); rsSue_Q  
String sProperty = "bytes="+nStartPos+"-"; p+D=}O  
httpConnection.setRequestProperty("RANGE",sProperty); b{HhS6<K?  
Utility.log(sProperty); Qu_EfmN|  
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InputStream input = httpConnection.getInputStream(); "8t\MKt(  
//logResponseHead(httpConnection); J8h7e}n?  
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byte[] b = new byte[1024]; 9UmBm#"  
int nRead; Y2vj}9jK  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) e-!?[Ujv*%  
{ "w^Nu6  
nStartPos += fileAccessI.write(b,0,nRead); & >b+loF  
//if(nThreadID == 1) _sm;HH7'*  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); 4Bo<44-,  
} C >kmIw'  
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Utility.log("Thread " + nThreadID + " is over!"); #`58F
.  
bDownOver = true; "8_,tYAH  
//nPos = fileAccessI.write (b,0,nRead); .P%ym~S  
} zW)gC9_|m-  
catch(Exception e){e.printStackTrace ();} >e_%M50  
} q4k`)?k9  
} k1wr/G'H[  
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//打印回应的头信息 ^hysCc  
public void logResponseHead(HttpURLConnection con) 7AeP Gr  
{ V@Kn24''  
for(int i=1;;i++) 4zX=3iBt  
{ Q%M_   
String header=con.getHeaderFieldKey(i); Dpj-{q7C  
if(header!=null)
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//responseHeaders.put(header,httpConnection.getHeaderField(header)); ~%KM3Vap  
Utility.log(header+" : "+con.getHeaderField(header)); 9RB`$5F;  
else '2wCP EC  
break; -4%]QS  
} <4sj@C  
} kyK'  
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public void splitterStop() :r^klJ(m  
{ 9^p32G  
bStop = true; @jKDj]\  
}
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- &NQ\W  
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} ${@q?iol  
/Bm#`?(ia  
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/* Kc-4W6?$  
**FileAccess.java v#Sj|47  
*//文件访问(定位，写) 'Y ,1OK  
package NetFox; fIH#  
import java.io.*; kLq(!Gs  
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public class FileAccessI implements Serializable{ yz8-&4YRNd  
J2'W =r_#  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 =9fEv,Jk  
RandomAccessFile oSavedFile; SF"#\{cjj  
long nPos; k=ts&9\  
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public FileAccessI() throws IOException TZj[O1E  
{ qj`,qm P  
this("",0); "I@v&(Am;  
} CJm.K  
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public FileAccessI(String sName,long nPos) throws IOException "*+\KPCU  
{ 8,_ -0_^$  
oSavedFile = new RandomAccessFile(sName,"rw"); _HLC>pH~#  
this.nPos = nPos; /%5_~Jkr,  
oSavedFile.seek(nPos); ;m''9z)2  
} E*OG-r   
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public synchronized int write(byte[] b,int nStart,int nLen) rAM*\=  
{ u]P03B  
int n = -1; hEWx.  
try{ 0~qf-x  
oSavedFile.write(b,nStart,nLen); L 43`^;u  
n = nLen; Ut]2`8-  
} 'YBi5_  
catch(IOException e) |PI)A`  
{ =l_rAj~I|  
e.printStackTrace (); B;SzuCW  
} DCt\
E/  
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return n; l<W*/}3  
} *X~B-a|nJ  
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} m5)EQE}gPp  
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/* v#iFQVBq  
**SiteInfoBean.java Cy<T Vk8  
*/ : #3OcD4  
package NetFox; ~
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09G9nu;&{  
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public class SiteInfoBean {  dhZZb  
}iD$4\ L  
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private String sSiteURL; //Site's URL =E&24  
private String sFilePath; //Saved File's Path {5U1`
>  
private String sFileName; //Saved File's Name 
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private int nSplitter; //Count of Splited Downloading File 5.O-(eSa0&  
l8er$8S}  
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public SiteInfoBean()
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{//nSplitter的缺省值为5 1po"gVot  
//default value of nSplitter is 5 "fRlEO[9  
this("","","",5); {EOn
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} C5>{Q:.`e'  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) 03~+-h&n  
{ F='Xj@&O  
sSiteURL= sURL; ;&K3[;a  
sFilePath = sPath; #D= tX  
sFileName = sName; P\,F1N_?r  
this.nSplitter = nSpiltter; v$[ @]`  
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} Y=5!QLV4  
;:AG2z
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/ c+,  
public String getSSiteURL() N{ : [/  
{ \k|_&hG  
return sSiteURL; xR0~S 3caI  
} yEE|e&#>  
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public void setSSiteURL(String value) Tq9,c#}&  
{ #x, ]D  
sSiteURL = value; 2ZU@>W  
} ''$`;?t>  
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public String getSFilePath() 2
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{ U#8\#jo  
return sFilePath; D9}d]9]$  
} "B3iX@C  
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public void setSFilePath(String value) g ^D)x[  
{ ;~}-AI-  
sFilePath = value; }9MW!Ss  
} 4aj[5fhb-  
F;cI0kP=>  
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public String getSFileName() 29R_n)ne  
{ +#|'|}j  
return sFileName; ;6DR.2}?>  
} EZ:I$X  
$ 1akI  
zb@L)%  
public void setSFileName(String value) RH<@c^ S  
{ nvU+XCx  
sFileName = value; Ytl:YzXCi  
} o@qN#Mg?>}  
sL!;hKK  
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public int getNSplitter() L~^e\^sP  
{ 1.hOE>A%  
return nSplitter; +9<,3IJe6  
} K?z*3^^X;  
u+%)JhIp  
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public void setNSplitter(int nCount) [{6&.v  
{ /V#MLPA  
nSplitter = nCount; 5A0KV7N5  
} nG&w0de<>  
} D]t~S1ycG7  
t:?<0yfp&  
B|$\

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/* H @3$1h&YS  
**Utility.java !1ie:z>s  
*/ [i,5>YIk
 
package NetFox; )a4E&D  
,U|u-.~ZU  
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public class Utility { +=n x|:no  
}e&KO?x+  
 y)N.LS  
public Utility() >m)2ox_B  
{ ~G|{qVO7A  
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} pl1EJ <  
,g<>`={kK+  
//线程睡眠 :kf3_?9rc  
public static void sleep(int nSecond) [#H
8=  
{ @B>%B EC  
try{ : L6-{9$  
Thread.sleep(nSecond); GI'&g@?u  
} L<[
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catch(Exception e) [)b/uR  
{ [T$$od[.  
e.printStackTrace (); ^)eessZ  
} N7j]yvE  
} FM@W>+  
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//日志 K'{wncumQ  
public static void log(String sMsg) MJ*oeI!.=  
{ n@yd{Rc  
System.err.println(sMsg); TkoCyD9  
} % @^VrhS  
(rY1O:*S  
Oy?iAQ+  
public static void log(int sMsg) ek+8hnkh  
{ ~'PS|  
System.err.println(sMsg); K>DnD0  
} z
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} X*p:&=o  

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/* #!<+:y'S?  
**TestMethod.java ]0/~6f  
*/ +Qb2LR  
package NetFox; ]UpHD.Of[t  
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.{Eg(1At  
public class TestMethod { }E)8soQR  
x""Mxn]gD  
*YEIG#`  
public TestMethod() %]P@G^Bv  
{ ///xx/weblogic60b2_win.exe h
} b^o*  
try{ LcQ\?]w`]  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); {?h6*>-^Z  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); Y GcY2p<  
SiteFileFetch fileFetch = new SiteFileFetch(bean); !513rNO  
fileFetch.start(); JzS^9)&  
} EC\rh](d 1  
catch(Exception e){e.printStackTrace ();} v#AO\zYKd  
`P)64So-1  
< 8W:ij.`  
} A%sxMA!K,  
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:ayO+fr#  
public static void main(String[] args) H 29 _ /  
{ ?M1 Q
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new TestMethod(); 0,
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} -7A!2mRiz  
} A`r$fCt1Vi  
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